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Full text of "soil analysis"

Current Trends In 
Mycorrhizal Research 



flntormati 
I sciences 
Arc^C^ 



EDITORS : BUSHAN L. JALALF AND' H. CHAND 






TATA ENERGY RESEARCH INSTITUTE 


1 


DEPARTMENT OF BIOTECHNOLOGY 


ARCHIV 


DEPARTMENT OF SCIENCE AND TECHNOLOGY 


52749 


AND 
J^ARYtfNA AGRICULTURAL UNIVERSITY 



I 



IDRC-Ub 

CURRENT TRENDS lKf RCUB 
MYCORRfflZAL RESEARCH 





PROCEEDINGS OF THE 

NATIONAL CONFERENCE ON MYCORRHIZA 

At Haryana Agricultural University, Hisar 
February 14-16, 1990 



EDITORS 
BUSHAN L. JALALI AND H. CHAND 

DEPARTMENT OF PLANT PATHOLOGY 
HARYANA AGRICULTURAL UNIVERSITY, HISAR, INDIA 



In Collaboration With : 

TATA ENERGY RESEARCH INSTITUTE 

DEPARTMENT OF BIOTECHNOLOGY 

DEPARTMENT OF SCIENCE & TECHNOLOGY 

$$i ,5-5,00/, 5 

This work is used with the permission of The Energy and Resource Institute. |Vf ^ 

\ Qf q q 

si-Resource Institute, ^ 



This report is presented as received by IDRC from project recipient(s). 
It has not been subjected to peer review or other review processes. 



PREFACE 

To him who devotes his life to science, nothing can give more happiness than 
making discoveries, but his cup of joy is full only when the results of his studies find 
practical application. 

— Louis Pasteur 

This dictum is relevent even today, particularly so in the field of mycorrhizal 
research. No doubt, considerable progress has been made, over the years, in 
furthering knowledge on various dimensions of mycorrhizas. Inoculation of 
agricultural crop plants and forest trees with mycorrhizal fungi has been convincingly 
demonstrated to stimulate their growth and development. Such probiotic effects are 
particularly striking in nutritionally poor soils, which abound in large areas of the 
arid and semi-arid tropics. The significant impact of mycorrhiza can easily be 
realised from the fact that almost all plant species of economic importance 
growing under diverse agro-climatic conditions are able to be infected; most form 
vesicular-arbuscular mycorrhiza, and several tree species form ectomycorrhiza. Most 
of the experimental work have amply demonstrated the physiological benefits that are 
conferred by mycorrhizal endophyte on their potential host plants, and such effects 
have been explained in terms of measurable enhancement of phosphate transport. 
Another dimension of immediate relevance is their role in induced suppression of 
soil/root-borne pathogens,-a group of diseases which are otherwise difficult to control 
by conventional fungicidal applications. No less important is the part they play in 
conferring resistance to water stress, as well as decreased leakage of electrolytes from 
cells of diseased plants. 

Substantial quantum of information has been generated on these and other 
aspects at various research centres of the world. Realising the importance of this 
microbial model system in enhancing crop productivity, concerted efforts have been 
made in India and other Asian countries to strengthen and mobilise the research 
endeavours in a cohesive manner. 

A step forward in this direction has been the establishment of Mycorrhiza 
Network Asia Project at TERI, launched recently to strengthen research, encourage 
cooperation and promote exchange of information in this important field. In its very 
first meeting held in January, 1989, the Technical Advisory Committee of this 
Network decided to organise the 'National Conference on Mycorrhiza' at Haryana 
Agricultural University, Hisar. 



The primary objective of this conference was to bring together active 
mycorrhiza researchers to highlight the state of art in this thrust area, review progress, 
project future goals and to identify constraints, so as to help give momentum to this 
field of research. Keeping the Asian scenario in view, the scientific programme was 
tailored to five technical sessions comprising of : Ecology, Physiology/Biochemistry, 
Biological Interactions, Biocides, and Soil-Plant Relationships. 

To sustain the impact of this conference, the Organising Committee decided 
to make this publication available at the time of conference rather than deferring it 
to a later date. Thus, the present publication entitled "Current Trends in 
Mycorrhizal Research", embodies the invited as well as contributed papers, submitted 
in the form of 'extended abstracts'. 

The mission has been to ascertain where we stand today, and then to look 
forward to the problems that may challenge us in decades ahead. This publication, 
hopefully, will highlight the different directions that mycorrhizal research has taken 
in recent years in India and other Asian countries. This should eventually help to 
strengthen our efforts in launching newer areas of investigation in the years to come. 

Time has come when we must concentrate more mycorrhizal research on 
"Does it work in the field" rather than "How does it work in the laboratory", so as 
to harness its utility and applicability in promoting economic gains. 

Department of Plant Pathology, Bushan L, Jalali 

Haryana Agricultural University, H. Chand 

Hisar-125 004, India 



A WORD OF GRATITUDE 

I am deeply indebted to the members of the Steering Committee and the 
Organising Committee for their, valuable advice and guidance in the smooth 
conductance of the conference. Equally important was the liberal support and 
cooperation received from Tata Energy Research Institute, Department of Biotechno- 
logy, and Department of Science & Technology, Government of India. 

I count myself fortunate to have had such an understanding and ever-helpful 
circle of dedicated faculty of plant pathologists at H. A. U., who have put in lot of 
effort for the success of this conference. Sincere thanks to the authors who contri- 
buted to this volume; obviously, their timely contributions have made this publication 
possible. 

I owe a great deal to each of them. If any credit is due^ it is to them. 
Criticisms that are surely to arise are mine to endure. 



1 L. Jalali 

Conference Coordinator 



NATIONAL CONFERENCE ON MYCORRHIZA 



(a) STEERING COMMITTEE 



Dr. Har Swamp Singh 
Dr. R. K. Pachauri 
Dr. V. Gowarikar 
Dr. R. S. Paroda 
Dr. H. K. Srivastava 

(b) ORGANIZING COMMITTEE 

Dr. M. L. Sharma 
Dr. S. P. S. Karwasra 
Dr. M. L. Pandita 
Dr. K. V. B. R. Tilak 
Prof. A. Mahadeven 
Mr. Sujan Singh 
Dr. Sunil Khanna 
Dr. J. N. Chand 
Dr. R. D. Parashar 
Dr. Satyavir 
Dr. M. P. Srivastava 
Dr. G. S. Saharan 
Dr. B. L. Jalali 



Vice-Chancellor, HAU 
Director, TERI 
Secretary, DST 
DDG, ICAR 
Coordinator, DBT 



Dean, P.G.S., HAU 
Director Research, HAU 
Dean, COA, HAU 
IARI, New Delhi 
CAS, Bot. Madras 
TERI, New Delhi 
TERI, New Delhi 
Dept. PI. Path., HAU 



Conference Coordinator 



CONTENTS 

PREFACE 

SECTION I : ECOLOGY 

Vesicular-arbuscular mycorrhiza in aquatics 1 

— F. Bareen 

Vesicular-arbuscular mycorrhiza in portions other than root 4 

— G. Nasim 

Mycorrhizal relations of successional stages of mangrove vegetation at the 
Ganges river estuary in India 7 

— S. Chaudhuri and A. Sengupta 

Spore populations of VAM fungi in foxtail millet fields of Anantapur district, 
Andhra Pradesh 10 

— T. Padmavathi, J. Veeraswamy and K. Venkateswarlu 

Response of a shola plant, Rhododendron nigricans to endomycorrhizal 
inoculation 1 1 

— R. Narayanan, M. Rangarajan and D. Kandasamy 

Ectomycorrhizal fungi associated with different forest trees of Himachal 
Pradesh 13 

—B. M. Sharma and B. M. Singh 

Survey of native VAM fungi of saline soils of Haryana state 16 

— H. S. Thapar and K. Uniyal 

Impact of season on the distribution of VAM fungi associated with sesame 18 

— T. Sulochcma and C. Manoharachary 

Density of vesicular-arbuscular mycorrhizal fungi in different crops grown 
under black soil 20 

-P. C. Hiremath, K. M. Harini Kumar and C. V. Patil 

Mycorrhizal investigations in some orchids 22 

—P. Kaushik, S. K. Sharma and S. Kumar 

Incidence of vesicular-arbuscular mycorrhizal fungi in Raipur soils 24 

—N. Gupta and S. S. Ali 



Mycorrhizal reproduction as influenced by moisture stress 

— G. Pai, D. J. Bagyaraj and T. G. Prasad 

Studies on the mycorrhiza of apple (Malus domestica Borkh.) 

— M. Thakur and T. N. Lakhanpal 

Occurrence and distribution of vesicular-arbuscular mycorrhizal fungi in acid 
soils of North-Eastern India 

— M. N. Venkataraman, R. Kotoky and H. D. Singh 

Preliminary survey of mycorrhizal fungi in some weeds and cultivated plants 
in Meerut 

—S. K. Rathi and L. Singh 

Extraction of vesicular-arbuscular mycorrhizae spores and effect of fertilizers 
on their population in oil seeds-cropped soils 

-B. N. Shukla and N. Vanjare 

Suitable source and level of nitrogen for mass production of the VA- 
mycorrhizal fungus Glomus fasciculatum 

— M. N. Sreenivasa and D. J. Bagyaraj 

Nutrient release from litter and the development of mycorrhizae in more 
disturbed and less disturbed forest communities 

— S. Kshattriya, D. K. Jha, G. D. Sharma and R. R. Mishra 

Spore dispersal of endogonaceae by worms, wasps, dung rollers and Indian 
domestic fowls 

— H. C. Lakshman and S. Raghavendra 

Survey of Indian arid zone tree species for the occurrence of VAM infections 
-/. C- Tarafdar and A. V. Rao 

VAM fungi from the rhizospheres of desert cacti 

— /. Mathew, Neeraj, A. Shankar, R. Kaur and A. Varma 

Occurrence of VA-mycorrhizal associations with fruit and ornamental plants 
— K. P. Raverkar, K. Mehta and A. R. Bhandari 

SECTION II : PHYSIOLOGY/BIOCHEMISTRY 

Growth and nutrient uptake of Eucalyptus camaldulensis and Pinus caribaea 
var. hondurensis seedlings grown on old tin-mined soils after Pisolithus 
tinctorius ectomycorrhizal inoculation and manure fertilization 

— A. Chalermpongse and S. Boonyuen 

Photoassimilate partitioning and translocation in mycorrhizal sorghum 

~M. Singh and K. V. B. R. Tilak 



Sporulation in Glomus mosseae under in vitro conditions 

— A. Adholeya and S. Khanna 

Enhanced phosphatase activity in mycorrhizal papaya (Carica papaya cv. 
Coorg Honey Dew) roots 

— S. Mohandas 

Characterization of mycorrhiza-specific alkaline phosphatase from french bean 
— K. Kumari, D. P. Mishra and B. N. Johri 
Nitrate reductase activity of vesicular-arbuscular mycorrhizal fungi 

— K. V. B. R. Tildk and Dwivedi 
The response of mycorrhizal maize plants to variations in water potentials 

—B. Ramakrishnan, B. N. Johri and R. K. Gupta 
Effect of soil degradation on soil microbes, symbionts and their activities 

— D. K. Jha, S. Kshattriya, G. D. Sharma and R. R. Mishra 
Effect of pH on the growth of ectomycorrhizal fungi in vitro 

—B N. Jha, G. D. Sharma and R. R. Mishra 

Phosphate response curve of Leucaena inoculated witn Gigaspora margarita 

—M. S. Byra Reddy, D. J. Bagyaraj and B. C. Mallesha 
Response of different cultivars of sorghum {Sorghum vulgare) to inoculation 
with Glomus versiforme 

—M. Singh and K. V. B. R. Tilak 

Influence of vesicular-arbuscular mycorrhizae on the photosynthesis and 
photorespiration of sweet potato (Ipomoea batatas) 

~V. P. Potty and P. Indira 

Effect of foliar application of urea on nitrogen metabolism of mycorrhizal 
moong plants under varying phosphorus levels 

— S. Thapar, B. S. Sekhon, A. Atwal and R. Singh 

SECTION III .• BIOLOGICAL INTERACTIONS 

Biological interactions between VA mycorrhizal fungi and other beneficial 
soil organisms 

—D. J. Bagyaraj 

Interactions of mycorrhizal fungi with root pathogen of cocoa 

— A. H. Chulan, G. T. ShajiandZ. A. Christine 

Biotechnology for mass production of VA-mycorrhiza inocula 

— S. N. Singh 



Interaction of VA-mycorrhizae with beneficial soil microorganisms 87 

— K. V. B. R. Tilak 

Mycorrhiza induced resistance, a mechanism for management of crop diseases 91 

— P. Vidhyasekaran 

Interaction study of Glomus mosseae and Rhizoctonia solani 94 

-B. R. Khadge, L. L. Hag and T. W. Mew 

Mechanism of resistance of mycorrhizal tomato against root-knot nematode 96 

— Y. P. Singh, R. S. Singh and K. Sitaramaiah 
Antagonism of ectomycorrhizal fungi to some common root pathogens 98 

—K. Natarajan and V. Govindasamy 

Influence of VA-mycorrhizal colonization on root-knot nematode infestation 
in Piper nigrum L. 100 

—P. Sivaprasad, A. Jacob, S. K. Nair and B. George 

The role of VA-mycorrhiza in controlling certain root diseases of tobacco 102 

— D. V. Subhashini 

Prevalence of nacive VAM fungi and their relative performance in inactivity 
of local crops 103 

— C. N. Reddy and R. S. Bais 

Role of VA-mycorrhizae, phosphate solubilising bacteria and their inter- 
actions on growth and uptake of nutrients by wheat crop 105 
— A. C. Gaur and J. P. S. Rana 

Interaction of vesicular-arbuscular mycorrhiza (Glomus etunicatum) and 
Rhizobium in cowpea 107 

—B. Ramaraj and N. Shanmugam 

Interaction between Glomus versiforme and Azospirillum brasilense in barley 109 

— M. Negi andK. V. B. R. Tilak 

Vesicular-arbuscular mycorrhizal associations and root colonization in some 
important tree species 111 

— H. S. Thapar and A. K. Vijayan 

Interaction between Glomus fasciculatum and two phosphate solubilizing fungi 
in finger millet 113 

— M. N. Gopalakrishna, D. J. Bagyraj and M. Vasanthakrishna 

Infection by a fungal endophyte, Balansia sclerotica enhances vesicular- 
arbuscular mycorrhizal (VAM) association in lemongrass 115 
— K. K. Janardhanan, A. Ahmad and M. L. Gupta 

, iv 



Endophytic mycorrhiza in different varieties of Ltichi chlnensis Sonn. and its 

effect on rhizosphere-microbial population 1 17 

-5". Pandey and V. K. Singh 
Interaction of VA mycorrhizal fungus and Tylenchulus semipenetrans on citrus 118 
-PP. S. Baghel, D. S. Bhatti and B. L. Mali 

Responses of dual inoculation with Bradyrhizobium and VA mycorrhiza or 
phosphate solubilizers on soybean in mollisol 120 

~H. P. Singh 

' SECTION IV : SOIL-PLANT RELATIONSHIPS 

Clonal selectivity in Populs deltoides for vesicular-arbuscular mycorrhizal 
association 122 

— O. P. Sidhu, P. N. Misra and H. M. Behl 

Interactions between isolates of ectomycorrhizal Lacccvia spp. and root rot 
fungi of conifers 124 

— K. Sampangiramaiah and R. Perrin 

Studies on the growth of certain ectomycorrhizal fungi in culture media and 
to the host under axenic conditions 126 

— M. Rangarajan, R. Narayanan, D. Kandasamy and G. Oblisami 

The mycorrhizal association of morels in N. W. Himalayas 128 

-0. Shad, A. Sagar andT. N. Lakhanpal 
Relative efficacy of VAM isolates for green gram under water stress conditions 130 
-H. K. Kehri and S. Chandra 

Effect of interaction between VA-mycorrhizae and graded levels of phosphorus 
on the growth of papaya (Carica papaya) 133 

— T. M. R. Padma and D. Kandasamy 

Influence of VA-mycorrhizal inoculation on growth and development of 
rapeseed 135 

—P. P. Gupta, M. L. Chhabra, B. L. Mali and P. R. Kumar 
Role of endomycorrhizae in fuelwood plantation nurseries for alkaline soil sites 137 

— H. M. Behl 

A strategy for selection and application of VAM fungi for Glycine max 139 

— A. Kapoor and K. G. Mukerji 

Effect of different VAM fungi under varying levels of phosphorus on growth 
and nutrition uptake of pigeonpea (Cajanus cajari) 141 

— R. S. Champawat 



Effect of superphosphate, rock phosphate as sources of phosphorus in 
combination with Glomus fasciculatum on root colonization, growth and 
chemical composition of blackgram 

— G. Uma Devi and K Sitaramaiah 

Response of brinjal genotypes in term of dry weight and phosphorus uptake 
as influenced by VAM inoculation 

— D. V. Indi, B. K Konde and K R. Sonar 
Improved yields in potato through mycorrhizal inoculations 

—R.P.Rai 

Studies on vesicular-arbuscular (VA) mycorrhizal impact on growth and 
development of cowpea (Vigna unquiculata (L.) Walp) 

—M. L. Chhabra, R. P. Singh and B. L. Mali 

Vesicular-arbuscular (VA) mycorrhiza in presence of Rhizobium sp. enhances 
nodulation, N 2 fixation, N utilization of pigeonpea (Cajanus cajan) as assessed 
with a 15 N technique 

—C. S. Singh 
Effect of interaction between Rhizobium and VA mycorrhizal fungi inoculation 
on the growth of groundnut applied with different levels of gypsum 

—P. Santhanakrishnan and G. Oblisami 
Yield and nutrient uptake by brinjal as influenced by Azospirillum brasilense 
and/or Glomus fasciculatum inoculations under graded phosphorus levels 

— D. V. Indi, B. K Konde, P. V. Wani and P.N. Kale 
Mycorrhizal status of some desert plants and their physiological significance 

—A. Shankar, J. Mathew, Neeraj, R. Kaur, R. S. Mehrotra and A. Varma 
Distribution and intensity of native VAM in Maharashtra region 

— V. P. Rao, S. E. Pawar and S. N. Singh 

The occurrence of vesicular-arbuscular mycorrhizal fungi in arable soils of 
Konkan region of Maharashtra 

— S. Dalai and K.V. Hippalgoankar 
Interaction between Rhizobium, mycorrhiza, nitrogen and phosphorus and 
their effect on growth and symbiotic behaviour of Leucaena leucocephala 

— R.P. Gupta and V. Pun) 
Vesicular-arbuscular mycorrhizal associations in Glycine max (L.) Merrill, 
improves the symbiotic nitrogen fixation under water stress 

-K P. Raverkar, A. Dwivedi and K V. B. R. Tilak 



Effect of VAM on mulberry cultivation : New avenues of VAM application 171 

— D. Rajagopal and K. Jamil 

SECTION V : BIOCIDES 

Side-effects of pesticides on mycorrhizal system-an overview 172 

-B. L. Mali 

Interaction between vesicular-arbuscular mycorrhizal fungi and fungicides 175 

—S. C. Vyas and V. N. Shroff 

Interaction of dual inoculation of VA-mycorrhiza and Rhizobium with 
pesticides treated chickpea plants 178 

—B. L. Mali, M. L. Chhabra and R. P. Singh 

Effects of fungicides on vesicular-arbuscular mycorrhizal association and 
plant growth response of citrus seedlings 180 

— R. S. Singh, H. Singh and O. S. Singh 

Effect of methyl isocyanate on vesicular-arbuscular mycorrhizal fungi 182 

— V. Mohankumar and C. B. Nirmala 

Effect of dichlone on Nostoc and VAM 184 

— S. L. Gupta 

Pesticides-mycorrhiza interactions on the growth and development of 
pigeonpea {Cajanus cajan) 186 

—R.P. Singh, M. L. Chhabra and B. L. Mali 

Effect of fungicides on mycorrhizal and rhizobial development in soybean 188 

—S. C. Vyas, A. Vyas, K. C. Mahajan and V. N. Shroff 

Effect of insecticides on wheat crop inoculated with phosphate solubilizing 
bacteria (PSB) and VAM fungi 190 

— A. C. Gaur and J. P. S. Rana 
Recent advances and trends in ectomycorrhizal research 191 

—H. S. Thapar 
Desert Plantation and mycorrhizae-current state of art 193 

— A. Varma, Neeraj, R. Kaur and A. Shankar 

Vesicular-arbuscular mycorrhizal root colonization and spore production in 
maize inoculated with Glomus fasciculatum 196 

—P. Nadarajah and A. Nawami 

Development of ectomycorrhizae on pine and its effect on the growth of 
Pinus kesiya under different moisture regimes 199 

— Raj Kumar, G. D. Sharma and R. R. Mishra 



Identification of endogonaceous fungi from Delhi 

— Q. Z. Khan and A. K. Sarbhoy 

Interactions between Rhizobium (cowpea miscellany) and mycorrhizal fungi 
and their stimulatory effects on Acacia nilotlca (L.) Del. 

—Pramila Sharma, R. Niranjan, Banwarilal and V. M. Rao 
Studies on the effect of Rhizobium (cowpea miscellany) and endomycorrhizal 
interaction in Dalbergia sissoo (Roxb.) 

— R. Niranjan, Pramila Sharma, Banwarilal and V. M. Rao 

Nitrogen and carbon nutrition studies of endophytes of ophioglossales 

-L. N. Nair 

Distribution of VAM in Tamil Nadu 

— V. Ganesan, B. Balajee, CGopalkrishnan and A. Mahadevan 



Vesicular arbuscular mycorrhiza in aquatics 

FIRDAUS-E-BAREEN 

Department of Botany, University of the Punjab, 
Quaid-e-Azam Campus, Lahore-20 

Hydrophytes were regarded non-mycorrhizal until the last decade (Gerdemann, 
1975). They could become mycorhizal under a change from wet to drier conditions 
(Read et al., 1976). There are only a few reports on the occurrence of VA mycorrhizal 
endophytes in natural aquatic conditions. Rayner (1927) observed VAM fungi in 
bogs. Dowding (1959) noted VAM fungi in roots of four swamp plants and swamp 
mud. Khan (1974) observed that none of the hydrophytes under study colonized 
VAM fungi though a low frequency of spores occurred in their rhizosphere. Read 
et al. (1976) found mycorrhizal colonization almost neglegible in marsh plants. 
Sondergaard and Laegaard (1977) observed five out of seven temperate aquatic plants 
mycorrhizal. 

Bagyaraj et al. (1979) were the first to report VA mycorhiza in non-root part 
of any hydrophyte (modified leaves of Salvinia cucullata). 

The present survey was conducted to observe the VA mycorrhizal status of 
some common aquatics in ponds and marshes of the Punjab. 

Mycorrhizal status of the common aquatics namely Azolla pinnata R. Br., Chara 
sp., Ceratophyllum dtmersun luinn., Cyperus eleusinoides Kunth., Eicchornia crassipes 
(Mart.) Solms., Equlsetum arvense Linn., Hydrilla verticillata Royle, Lemna polyrrhiza 
Linn., L. paucicostata Hegelm., Marsilea quadrifoliata Linn., Najas major All., 
Nelumbium nelumbo (Linn.) Druce, Nymphaea lotus Linn., N. stellata WiM.,Phragmites 
kirka Linn., Pistia stratiotes Linn., Polygonum barbatum Linn., Potamogeton crispus 
Linn., P. pectinatus Linn., Ranunculus aquatilis Linn., Sagittaria guayanensis Kunth., 
Salvinia cucullata Roxb., Trapa bispinosa Roxb., Typha angustata Chaub & Bory., 
Vallisneria spiralis Linn, and Zannichellia palustris Linn, was observed. VA mycorrhi- 
zal colonization was observed in rhizoids of Chara sp. (Iqbal et al., 1988) and roots 
of Azolla pinnata, Eicchornia crassipes, Equisetum arvense, Marsilea quadrifoliata, 
Phragmites kirka and Ranunculus aquatilis. In non-root plant parts mycorrhizal 
colonization was observed in leaves of Azolla pinnata (Iqbal and Firdaus-e-Bareen, 
1989); senescing leaves and stem of CeratophyUum demersum; dried scales on leaves of 
Eicchornia crassipes; senescing leaves of Equisetum arvense (Nasim et al; 1987), Lemna 
spp., Nymphaea lotus, Typha angustata; and modified leaves of Salvinia cucullata (Iqbal 
and Firdaus-e.-Bareen, 1989) and Trapa bispinosa. 

[ 1 ] 



Multiple VA infections occurred in most cases as many kinds of vesicles were 
observed. Oil droplets characteristics of the aquatic environment could be observed 
in most plants (Bagyaraj, et al., 1979). Arbuscules were totally absent. 

A low frequency of endogonaceous spores was found in the rhizosphere of 
most plants. Many species of Glomus and Acaulospora sp. were actually observed 
causing infections in non-root plant parts in the aquatic environment. 

The occurrence of mycorrhiza in aquatic conditions indicates that it must be 
playing some role in nutrient absorption especially in plants growing in nutritionally 
poor sediments. The special shapes of vesicles with prominant oil droplets shows the 
adaptation of VA mycorrhizal symbionts according to the environment. The 
occurrence of mycorrhiza or its absence in the same plant in ecologically different 
conditions indicates that the ecological and environmental conditions (both qualitative 
and quantitative) seem to have a great influence on the colonization of plants. The 
variation in colonization from place to place could also be due to several other 
environmental factors. 

The plants tend to acquire mycorrhizal colonization in drier conditions (Iqbal 
and Firdaus-e-Bareen, 1989). This is obvious as greater colonization was observed 
in semi-aquatics or aquatics in marshy places. Once the VAM endophyte causes 
infection in a ., plant, aquatic conditions can not reduce the intensity of colonization 
(Bagyaraj et al., 1979). Most probably the lesser colonization in aquatic conditions 
is because of low availability of spores or other types of efficient inocula. Low 
availability of spores in aquatic or water-logged conditions could be directly attributed 
to soil aeration (Saif, 1981). The colonization of non-root parts of aquatics show 
that VAM endophytes have greatly expanded and safer ecological niches. The 
decaying organic matter formed by leaves of common aquatics in marshes harboured 
VA endophytes. In our irrigation system in the Punjab this could become an 
efficient way of dispersal for VA endophytes and enhance fertility of soil as well. The 
decaying thalli of Azolla in dried rice fields acquire mycorrhizal infection. Methods 
could be formulated for artificially inducing VAM endophytes in biofertilizers like 
Azolla pinnata which forms dual symbiotic associations with Anabaena azollae and VA 
endophytes (Iqbal and Firdaus-e-Bareem, 1989). Under water-logged conditions in 
the paddy-fields it fixes nitrogen and under drier conditions it could fix phosphates. 

REFERENCES 

Bagyaraj, D. J., Munjunath, A., Patil, R. B. 1979. Occurrence of vesicular arbuscular mycorrhizas 
in some tropical aquatic plants. Trans, Brit. Mycol. Soc. 72 : 164-167. 

Dowding, E. S. 1959. Ecology of Endogone. Trans. Brit. Mycol. Soc. 42 : 449-457. 

Gerdemann, J. W. 1975. Vesicular arbuscular mycorrhizae. In : The Development and Function of 
Roots. Eds. J. G. Toney, D. T. Clarkson, Academic Press, London, pp. 575-591. 

Iqbal, S. H., Firdaus-e-Bareen. 1989. Vesicular arbuscular mycorrhiza] infections in th«S water 
ferns Salvinia cucullata Roxb. and Azolla pinnata R. Br. Biologia (in press). 

[ 2 ] 



Iqbal, S. H., Shahjahan, Nasim, G. 1988. Vesicular arbuscular mycorrhiza in an alga : Chara sp. 

Biologia 34:279-281. 
Khan, A. G. 1974. The occurrence of mycorrhizas in halophytes, hydrophytes and xerophytes and 

of Endogone spores in adjascent soils. /. Gen. Microbiol. 81 : 7-14. 
Nasim, G., Iqbal, S. H., Bhutta^, A. A. 1987- Equisetnm : An excellent host for VAM infections. 

Biologia 32 : 97-107. 
Rayner, M. C. 1927. Mycorrhiza. New Phytol. Reprint 15, pp. 246. 
Read, D. J., Kouchiki, H. K„ Hodgson, J, 1976. Vesicular arbussular mycorrhiza in natural 

vegetation system. New Phytol. 77 : 641-653. 
Saif, S. R. 1981. The influence of soil aeration on the efficiency of vesicular arbuscular mycorrhizae. 

I. Effect of soil oxygen on the growth and mineral uptake of Eupatorium odoratum L. 

inoculated with Glomus macrocarpus. New Phytol. 88 : 649-659. 
Sondergaard, M., Laegaard, S. 1977. Vesicular arbuscular mycorrhiza in some aquatic vascular 

plants. Nature 68 : 232-233. 



C 3 ) 



Vesicular arbuscular mycorrhiza in portions other than root 

GHAZALA NASIM 

Department of Botany, University of the Punjab, 

Quaid-«-Azam Campus, Lahore-20 

Vesicular arbuscular mycorrhiza is the most common type of all the 
mycorrhizae. This association not only facilitate the nutrient uptake, its effects on 
plant growth have also been revealed. 

The occurrence of VA mycorrhiza in roots has been reported from an exceptio- 
nally wide range of plants. However, the first report on its presence in portions 
other than roots i. e. modified submerged leaves of vascular aquatic plants in tropical 
conditions was by Bagyaraj et o/.(1979). They reported the presence of a mycorrhiza 
fungus in the root-like leaves of Salvinia, a rootless aquatic fern. Park & Linderman 
(1980) reported the occurrence of spores of VA mycorrhizal fungi in senescent leaves 
of a moss {Fumaria hygromatrica Sibth.). Glomus spores were observed in decaying 
peanut leaves in the field in Texas by Taber and Trappe (1982). The pegs of peanut 
plant have also been reported to harbour VA mycorrhiza (Graw and Rehm, 1977). 
Taber & Trappe (1982), for the first time reported the presence of VA mycorrhizal 
fungi in the vascular system of rhizomatous tissues and in scale like leaves of 
Zingiber officinale. 

The present study is focused to review the presence, nature and structure of 
VA mycorrhizal fungi associated with portions other than roots. This study is based 
on VA mycorrhizal investigations of herbaceous plants many of which were 
perennials. 

The plants studied for the presence of vesicular arbuscular mycorrhizal 
infections were Agremonia eupatoriutn, Allocasia indica, Arisaema spp., Cana indica, 
Cala aetheopica, Colocasia antiquorum, C. gigantea, Curcuma longa, C. zoedoria, 
Cyprus rotundus, Elettaria cardamomum, Musa paradisiaca, Oxalis corniculata, O. 
corymbosa, Plantago lanceolata, Polygonum sp., Primula sp., Saxifraga stracheyi, 
Sensevierea trifaciata, Sorghum halepense and viola spp. Some non-angiospermic 
plants were different spp. of ferns, Mosses, Bryophytes, Selaginella and Equisetum. 

The roots of almost all the plants studied had VA infections. Vesicles as well 
as arbuscules were present in many of the specimens but a few of them lacked 
arbuscules. Scale like leaves as well as epidermis of rhizomes of almost all the plants 
had VA infections. Vesicles were universally occurring while arbuscules were totally 

[ 4 ] 



lacking (Iqbal ef al., 1988; Nasim etal., 1989). In most of the cases the infections 
were multiple. Mostly the infections were caused by Glomus spp. It was indicated 
by the presence of Chlamydospores which are formed at a hyphal tip usually one per 
tip. In the scales were also observed spores mostly of the genus Glomus, borne singly 
on the hyphal tips e. g. in Colocasia antiquorum, Musa paradiasica (Iqbal and Nasim, 
1986). Azygospores of Gigaspora spp. were observed in scale of rhizome of Curcuma 
longa (Nasim, 1985) and Aresaema sp. The azygospores bud from the bulbous 
suspensor like tip of a hypha. Various types of Endogonaceous spores were found in 
the rhizospheres of Carta indica, Elettaria cardamomum and Curcuma longa (Nasim, 
1985). No arbuscules were found in the scales but highly branched and septate 
mycelium was very common inside as well as outside the cells. Septate mycelium 
and small endospore like structures were very common in the scale cells of rhizome 
of almost all the plants. Scales of the ihizomes of Carta indica, Colocasia antiquorum, 
Curcuma longa, Elettaria cardamomum, Musa paradiasica and Sansenieria trifaciata 
had very heavy (80-100%) vesicular infections (Nasim, 1985). The scale leaves of 
the rhizomes of Zingiber officinale, Colocasia gigantia, Oxalis spp. and of Sorghum 
halepense had moderate VA infections while those, of the rhizomes of Allocasia 
indica, Cala aethiopica, Aresaema sp., Plantago lanceolata, Saxifraga stracheyi, 
Viola spp., Polygonum sp., Agrimonia eupatorium had lower VA infections (Nasim, 
1985). Scales in many cases had multiple VA infections as is indicated by the 
vesicles size and width of the hyphae which were markedly different. 

This study extends the list of mycorrhizal plants consumed as food or used as 
medicines (Nasim et al., 1989). Mycorrhizal status of non-root portions of many 
plants has been reported for the very first time. Non-root portions had heavy 
vesicular infections and lacked arbuscular infections, instead the VAM mycelium 
became septated and filled the cell lumen at various instances. These septate hyphae 
probably functioned like arbuscules increasing the absorptive area (Iqbal et al., 1988; 
Nasim et al., 1989). Extramatrical spore formation was also observed at various 
places (Nasim et al., 1989). Occurrence of VA mycorrhizal fungi in this scale like 
portions which are probably dead suggests the saprophytic way of living of these fungi 
as indicated by Warner and Mosse (1980). The rhizomes corms and root stocks 
remain viable even after years and can be used as seeds for vegetative propagation. 
These underground portions are thus said to carry the VA mycorrhizal inoculum 
because when they are sown the VAM hyphae revive and the spore germinate 
(Iqbai and Nasim, 1986). Presence of these fungi in medicinally important 
plants suggests that these fungi are resistant to the active principal of these medici- 
nally important plants (Iqbal et al., 1988). The term "Mycorrhiza" was regarded 
inappropriate by Taber and Trappe (1982). They proposed the term "Mycophyllon" 
for leaf association and "Mycorrhizome" for rhizomatal associations (Iqbal and 
Nasim, 1986). 

[ 5 ] 



REFERENCES 

Bagyaraj, D., Munjunath, A., Patail, R.B. 1979. Occurrence of vesicular arbuscular mycorrhizas 

in some tropical aquatic plants. Trans. Brit. Mycol. Soc. 72 : 164-167. 
Graw, D., Rehm, S. 1977. Vesicular arbuscular mycorrhiza in den Fruchttaragern von Arachis 

hypogaea L. Zeitschrift fur Aker-und Pflanzenban 145 : 75-78. 
Iqbal, S.H., Nasim, G. 1986. Vesicular arbuscular mycorrhiza in roots and other underground 

parts of Zingiber officinale Roscoe. Biohgia 32 (1) : 273-377. 
Iqbal, S.H., Nasim, G. 1986. Vesicular arbuscular mycorrhiza in roots and rhizomatous (under- 
ground) portions of Musa paradisiaca. Biohgia 32 (1) : 279-282. 
Iqbal, S.H., Nasim, G., Shahjahan. 1988. III. Vesicular arbuscular mycorrhizal fungi associated 

with three mosses (Sphagnum cymbifolium, Polytrichum commune and Funaria hygromatrica) 

Biohgia 34 (2) : 29-33. 
Iqbal, S.H., Nasim, G., Shahjahan. 1988. I. Vesicular arbuscular mycorrhizal fungi associated 

with an alga (Chora sp-). Biohgia 34 (2) : 35-37. 
Nasim, G., Iqbal, S.H., Bhutta, A.A. 1989. Eauisetum : An excellent host for VAM infections. 

• Biohgia 33 (1) : 97-107. 
Nasim, G. 1985. Vesicular arbuscular mycorrhizae in roots and other underground plant organs of 

some angiosperms. M. Sc. Thesis, Punjab University, Lahore, Pakistan. 
Park, J.L., Linderman, R.G. 1980. Association of vesicular arbuscular fungi with the moss Funaria 

hygrometrica. Can. J. Bot. 58 : 1898-1904. 
Taber, R.A., Trappe, J.M. 1982. Vesicular arbuscular mycorrhiza in rhizomes, scale-like leaves, 

roots and xylem of ginger. Mycologia 74 ; 156-161. 
Warner, A., Mosse, B. 1980. Independent spread of vesicular arbuscular mycorrhizal fungi in soil. 

Trans. Brit. Mycol. Soc. 74 : 407-410. 



[ 6 3 



Mycorrhizal relations of successional stages of mangrove vegetation 
at the Ganges river estuary in India 

S. CHAUDHURI AND A. SENGUPTA 

Department of Plant Pathology 

Bidhan Chandra Krishi Viswavidyalaya, 

Kalyani-741 235, India 

Estuarine or maritime salt marshes are one of the most productive ecosystems 
of the world (odum, 1971). The tropical or sub-tropical parts such as saline wetlands 
are inhabited by mangroves, a climax formation of hydrohalophytes belonging to , 
several families. Besides for primary production of biomass, mangroves are also 
important as contributors to the complex geo-aquatic food web of the estuarine salt 
marsh ecosystems. 

Large areas of mangrove and other salt marsh centres of the world have been 
reclaimed aud replaced by diverse agro-ecosystems. Plant performance in these saline 
wetlands is generally poor due to salinity and inundation stress and also limitaiions 
of nutrients (Valiela and Teal, 1979). Knowledge regarding ecosytemic adaptations 
of mangroves may help in the conservation of such and other saline wastelands 
through plant culfure. In the context of our studies on microbiological aspects of 
ecosystemic adaptations of mangroves, mycorrhizal relations of the successional stages 
of mangrove vegetation at the terminal part of the Ganges river estuary (Sundarban) 
were examined. 

Based on floristic ecology and physiography macrophytic ecosystem of Sundar- 
ban was divided into four well distinct stages : I. Formative mangrove swamps on 
river beds, II. Tidally inundated well developed mangroves on raised beds, HI. 
Declining mangroves on inter-tidal ridges, and, IV. Declined mangroves on 
embankment protected highlands where saline agriculture and non-littoral tree forestry 
is practiced. The highly saline, clayey soils of the successional stages had very low 
nitrogen and phosphorus content. Organic matter content of particularly the well 
developed mangrove beds and protected agricultural lands were high. Fifty three 
plant species belonging to twentyfive families were present in these successional 
stages as true mangroves, mangrove associates and non-littoral, introduced but 
naturalised macrophytic flora. 

Root samples of plants collected from nine different locations representing 
the successional stages when examined by standard methods, revealed the presence of 
VA-mycorrhizal association in twentyfour mangroves, ten mangrove associates and 

t 7 ] 



eighteen non-littoral species. There were differences among the successional stages 
in root infection intensities of predominant plant colonizers. In general, root 
infection intensities of mangroves at the early successional stages were less than that 
of similar mangroves at the late successional stages. Within the latter, however, 
declined mangroves at the protected stage showed less infection than the declining 
mangroves at the inter-tidal ridges. Non-littorals including the common agricultural 
crops at the protected stage were also infected by VA-mycorrhiza. At the highly 
saline, inundation prone Hnd and Illrd successional stages non-mangroves showed 
less root infection than the true mangroves. At the protected stage root infection 
intensities of declined mangroves and all non-littorals considered together wefe 
comparable. But, at any of these stages non-mangrove trees were less infected than 
the tree mangroves. VA-mycorrhizal inoculum and spore densities of the successio- 
nal stage rhizosphere soils were inversely related with levels of soil water salinity and 
at only the protected stage were comparable to that of the common non-saline alluvial 
soils. 

Evidences obtained on natural root colonization, spore and inoculum densities 
and VAM infection of a large number of common herbs in transported successional 
stage soils were circumstantial for involvement of VA-mycorrhiza in plant colonization 
of the ecosystem. Edaphic and physiographic differences between esturaine and 
maritime mangrove habitats would explain some of the previous report about common 
absence of VA-mycorrhiza in mangrove habitats (Kannan and Lakshminarayan, 1989). 
Two ecologically variable VAM infection determining factors were operating in the 
ecosystem. As all other soil microorganisms, VA-mycorrhiza were also sensitive to 
salinity and inundation stress and ecologically variable soil physical-chemical factors 
appeared to be the primary determinants of VAM infection in the ecosystem. Plant 
genetic variations were significant only within a successional stage. Data further 
showed that within the mangrove ecosystem considerable adjustment exists between 
the natural plant colonizers and their mycorrhizal partners and ecosystemic changes 
not conducive to the natural plant colonizers might adversely alter the mycorrhizal 
relations. Exotic trees or plant species unnatural for the stress habitat may need 
time for adjustment with the existing VAM inoculum. 

Nine different Endogonaceous spore types were isolated from the soils of the 
ecosystem of which five were identified as belonging to the more common species of 
VA-mycorrhiza. Distribution of these spore types to the successional stages showed 
that there was probably no VA-mycorrhizal species specific for either the ecosystem 
or for any plant species. Histological and plant growth response data have shown 
that besides the typical VA-mycorrhiza, some atypical endophytes may also have 
mycorrhizal functions for such stress adapted plants of the ecosystem as has been 
reported for some other ecosystems also (Read and Haselwandter, 1981). 

[ 8 ] 



REFERENCES 

Kannan, K.. Lakshminarayan, C. 1989. Survey of VAM of maritime stand plants of Point 
Calimere. In : Mycorrhizae for Green Asia. Eds. A. Mahadevan, N. Raman, K. Natara- 
jan, University of Madras, India, pp. 53-55. 

Odum, E.P. 1971. Fundamentals of Ecology. 3rd Ed., W.B. Saunders, Philadelphia, U.S A. pp. 574. 

Read, D.J., Haselwandter, K. 1981. Observations of the mycorrhizal status of some alpine plant 
communities. New Phytol. 88 : 341-352. 

Valiela, I., Teal, J.M. 1979. N 2 budget of a salt marsh ecosystem. Nature 280 : 652. 



I 9 ] 



Spore populations of VAM fungi in foxtail millet fields of 
Anantapur district, Andhra Pradesh 

T. PADMAVATHI, J. VEERASWAMY AND K. VENKATESWARLU 

Department of Microbiology 

Sri Krishnadevaraya University 

Anantapur-515 003, Andhra Pradesh 

Numerous studies have indicated that vesicular-arbuscular mycorrihzas (VAM) 
are nearly ubiquitous for the majority of agricultural crops. The impact of VAM 
in tropical agriculture will be greater than in temperate regions, and the beneficial 
effects are dependent on their population density as well as species composition in 
the field soils. Foxtail millet is one of the major rain-fed crops being cultivated in 
the semi-arid soils of Anantapur district in Andhra Pradesh. No information is 
available on the occurrence of VAM fungi in such vast agricultural fields. The present 
study represents an attempt to establish the occurrence of spore populations of VAM 
fungi in the fields planted to foxtail millet. 

The five different places, within a radius of 50 km from Anantapur town, 
selected for the survey included Atmakur, Gangulagunta, Jangalapalli, Kondapuram 
and Miduthur. The agricultural fields in these localities consisted soils with varying 
physico-chemical characteristics. Root and rhizosphere soil samples were collected 
every 15 days after sowing the millet and were examined for the mycorrhizal spore 
populations. Foxtail millet raised in all different agricultural fields developed 
extensive mycorrhizas. The root systems as well as the rhizosphere soil samples 
showed varied populations of VAM fungi. Three species of Sclerocystis viz., S. 
sinuosa, S. clavispora and S. pakistanica were found to occur consistently at all places. 
The species of Glomus that most commonly occurred in heavy black soils were G. 
deserticola, G. etunicatum, G. fecundisporum, G. geosporum, G. invermaium, G. intrara- 
dices and G. tortuosum besides several unidentified isolates. In fields with alluvial 
soils, species of Gigaspora and Scutellospora were observed, in particular, along with 
the species of Glomus. 

The results of the present study indicate that VA mycorrhizas formed by a 
greater diversity of the endophytes, are quite extensive in fields of foxtail millet. 
Attempts are being made to exploit these biofertilizers by clearly appreciating the 
impact of the most abundant species of Glomus on growth, yield potential and 
drought-resistance of foxtail millet. 



[ 10 ] 



of a shola plant Rhododendron nigricans to 
endomycorrhizal inoculation 

R. NARAYANAN*, M. RANGARAJAN AND D. KANDASAMY 

Department of Agricultural Microbiology, 

Tamil Nadu Agricultural University, Coimbatore-641 003 

The natural vegetation of the upper region of Nilgiris consists of vast stretches 
of grassland interrupted with numerous isolated compact sharply defined broad leaved 
woods called sholas or montane evergreen forests. These shola forests occupy roughly 
20 per cent of the vegetation leaving the rest occupied by the grasses. These forests 
are mainly located in hill slopes or between mountain cliffs wherever soil moisture is 
high. Considerable destruction of sholas took place since the early days of human 
settlement. Among the shola vegetation, Rhododendron nilgricans is the most wide- 
spread plant. The root systems of several shola plants including R. nilgricans were 
reported to be associated with endomycorrhizae (Rangarajan et al, 1987). Experi- 
ments in unsterile soil frequently showed that introduced VAM-fungi can stimulate 
more nutrient uptake than the indigenous mycorrhizal fungi. However, the studies 
on the effect of VAM fungi in influencing the biomass production and nutrient 
uptake of the shola plants are scanty. Hence investigations were carried out to study 
the interaction of VAM fungi with Rhododendron nilgricans at Ooty. 

The soil used in the present study was an acid (pH 5.7) phosphorus deficient soil 
with 15 ppm of extractable P. Pots of 16.5 X 19.0 cm were filled with unsterile soil 
(3 kg/pot), which had endomycorrhizal population of 1.4 spores/g of soil. 

The soil-sand inoculum of eight VAM fungi were prepared by using maize 
(Zea mays), as host. The eight VAM-fungi included Glomus versicolor, G. mossae, 
Gigaspora margarita and Acaulospora laevis from University of Agricultural Sciences, 
Bangalore, Glomus fasciculatum, G. epigaeum and Acaulospora morroweae from 
Horticultural Research Station, Ooty and Glomus mosseae from Tamil Nadu Agricul- 
tural University, Coimbatore. The inoculum consisted of hyphae and spores of 
VAM fungi, infected root pieces of maize and soil having spore density of 35 spores/g 
of soil. A quantity of 10 g of inoculum was inoculated at the time of transplanting 
by placing the inoculum adjacent to the root zone (Schenck, 1982). Seedlings of 
R. nilgricans grown in natural sholas, were uprooted and planted in pots which were 
used for inoculation. 

♦Horticultural Research Station, Ooty 

[ 11 ] 



After the establishment of the seedlings in pots, the initial heights were 
recorded. Six months after the planting, the heights of the plants were again 
recorded. Percentage of increase in height as compared to the control was assessed 
to find out the efficiency of inoculation with individual VAM-fungus. 

Rhododendron nilgricans responded well to the inoculation with all eight VAM- 
fungi. The increase in height due to inoculation ranged from 15.85 to 39.02 per cent 
over control with maximum increase by Glomus mosseae from Bangalore. Effect of 
inoculation varied depending upon the fungus. While Glomus fasciculatum, Gigaspora 
margarita and Acaulospora laevis reported similar increase of 32.93 per cent over 
control, Glomus versicolor and G. epigaeum recorded 26.82 and 25.61 percent 
increase only. Less response to inoculation was observed with Acaulospora morroweae 
(19.51) and Glomus mosseae from Coimbatore (15.85). 

REFERENCES 

Rangarajan, M., Kandasamy, D., Narayanan, R., Ponnaiah, C, Govindarajan, K., Oblisami, 
G. 1987. Final Technical Report of D. OE. Project, pp. 38. ' 

Schenck, N. C. 1982. Methods and principles of mycorrhizal Research. Am. Physopath. Soc. St. 
Paul, U. S. A., pp. 444. 



C 12 J 



EctomycorrhizaJ fungi associated with different forest trees of 
Himachal Pradesh 

B. M. SHARMA AND B. M. SINGH 
H. P. Krishi Vishvavidyalaya, Palampur-176062 

Ectomycorrhizae are symbiotic associations between the hyphae of certain 
fungi and the roots of most forest trees including all members of pinaceae. The 
importance of ectomycorrhizae in the nutrition of most vascular plants and the health 
of forest ecosystems has been overwhelmingly demonstrated in recent decades (Marks 
and Kozlowski, 1973; Trappe and Fogel, 1977). 

Our present knowledge of the functions of ectomycorrhizae has come mainly 
from researches directed towards solving practical problems in forestry. Repeated 
failures in establishing exotic pine plantations in various parts of the world, where 
ectomycorrhizal hosts did not naturally occur, clearly demonstrated the dependence 
of these trees on their fungal symbionts (Mikola, 1970). A root system strongly 
mycorrhizal with proper beneficial fungi can vastly improve reforestation success with 
containerized nursery seedlings. 

There has been marked decrease in forest cover in Himachal Pradesh due to 
urbinization, construction, tree felling for fuel, timber and boxes for fruit packaging 
and forest fires. The process can be reversed by launching a massive reforestation 
pngramTU with appropriate spscies often in denuded and adverse, stressful sites. 
It has bsen ob served that nursery grown seedlings without mycorrhizae generally 
fail to establish in such sites. Thus, to achieve success in reforestation programme 
mycorrhizal inoculation at nursery stage with the appropriate fungal symbiont is 
essential. The present study was therefore undertaken to gather information on 
ectomycorrhizal fungi associated with different tree species in healthy forest sites in 
different altitudinal ranges of Himachal Pradesh. 

Periodic surveys were conducted during the monsoon season in 1987 and 1988 
to collect information on their distribution and host specificity. Species of higher 
fungi which were frequently found associated with particular type of host were preser- 
ved, dried and identified. Efforts were also made to bring in culture such species 
for their further evaluation in relation to different host species in containerized 
seedlings under controlled environmental conditions. 

The vegetation of Himachal Prahesh comprises purely coniferous, angiosper- 
mous or mixed forests as well as pastures in tropical, subtropical, temperate and 

[ 13 ] 



alpine regions. An account of the ectomycorrhizal species found frequently associa- 
ted with the forest trees in various zones of the state is given below : 

Pure formations of Pinus roxburghii are common in tropical zone at an 
altitude of about 700 m. The important ectomycorrhizal fungi collected from this 
zone were Scleroderma verrucosum, S. areolatum, S. dictyosporum, Rhizopogon spp. 
Suillus spp., Astreus hygrometricus, Amanita vaginata, Laccaria laccata and Lactarius 
sanguiflus. 

The important vegetational elements of subtropical zone are Pinus roxburghii, 
P. wallichiana, Quercus glauca, Q. incana, Acer oblongum and Ficus palmata. At some 
places, at an altitude of around 1800 m, Cedrus deodara forms an important compon- 
ent of vegetation. Mycorrhizal symbiosis appears to be highly pronounced in the 
mixed forests of 'deodar' and 'oaks'. The important fungal species found growing 
in association with Pinus roxburghii in this zone are mainly the species o' Amanita, 
Lepista nuda, Lactarius sanguiflus, Suillus sibricus, Boletus edulis, Cantharellus cibarius 
Scleroderma texense, Rhizopogon rubescense, Astreus hygrometricus and Thelephora 
terrestris. The important mycorrhizal symbionts of Cedrus deodara are several 
species of Amanita and Russula as well as Clitocybe infundlbuliformis, Lactarius 
deliciosus, L. zonarius, Leucopaxillus giganteus, Strobilomyces floccopus, Boletus edulis^ 
B. erythropus, Thelephora terrestris, Canthrellus cibarius and Laccaria laccata. In the 
forests dominated by oaks, several species of genus Russula are very common. The 
other species in oak forests are Agaricus augusius, Amanita muscaria var. flavivolvata, 
Collybia spp. Lactarius piperatus, L. zonarius, L. deliciosus, L, camphoratus, Stropharia 
rugosoannulata, Boletus edulis, Thelephora terrestris, Ramaria spp. and Scleroderma 
dictyosporum. 

The greater part of forests in temperate zone comprises oaks with rhododend- 
rons among the hard woods and blue pine, deodar, spruce and silver fir among the 
conifers in different belts according to altitude. The distribution of hardwoods and 
conifer trees in relation to altitude is as follows : 

Alt. in m Hard woods Conifers 

3000 Rhododendrons Abies pindrow 

2500 Quereus semicarpifolia A. pindrow 

2200 Q. dilatata A. pindrow 

P. smithiana 
2000 Q. incana Cedrus deodara 

Pinus wallichiana 

Ectomycorrhizal fungi are particularly abundant. Most of the species which 
occur in association with deodar and oaks in the sub-tropical zone are also present in 
this zone. However, some species like Clitocybe nebularis, Pluteus cervinus, 
Oudmansiella redicata, Lactarius detrinum, Gomphus floccosum, Helvetia atra and 

t H ] 



Sparssis crispa have been frequently found growing in association with deodar. 
Oak forests mixed with rhododendron also form an important component in 
this zone. This combination of vegetational elements has ectomycorrhizal species 
in the genera Ramaria and Russula. 

Abies pindrow and Picea smithiana form important components of forests in 
the higher ranges. Pure formation of these species has ectomycorrhizal species like 
Amanita pantherina, A. vaginata, Clitocybe gibba, Melanogaster durissimus and Sclero- 
derma tenerwn for A. pindrow and Hygrophorus pudorinus, H. chrysodon, Leucopaxi- 
llus amarus, Lactarius deliciosus, Suillus sibricus, Melanogaster spp. and Scleroderma 
spp. fori*, smithiana. 

Forests are few in alpine zone and these are confined to lower zone of this belt. 
The important tree found in the lower and intermediate zones are Quercus 
semicarpifolia, Rhododendron lepidotum and Salix tetrasperma showing stunted growth 
and rarely exceeding 10 m in height. Ectomycorrhizal fungi are rare in this zone. 
However, Paxillus involutus, Lepistanuda, Leucopaxillus sp. and Scleroderma areolatum 
have been found growing in association with Querus semicarpifolia and Salix 
tetrasperma. 

From the foregoing account on distribution of various ectomycorrhizal fungi 
in different forest types of Himachal Pradesh, it can be seen that many fungal species 
associate with a wide range of host plants e. g. Amanita pantherina, Lactarius 
sanguiflus, Boletus edulis, Laccaria laccata, Russula delica, Cantharellus cibarius and 
Thelephora terrestris to mention a few. Other species are more restricted in their 
distribution. For example species of Suillus and Rhizopogon mostly fruit under 
conifers particularly Pinus spp. However, true nature of host specificity is not clear. 
Tt is not understood whether a host-specific fungus forms mycorrhizae only with the 
host under which it fruits, or can it form mycorrhizae with many hosts but fruit only 
in association with certain ones. To understand the host specificity of ectamycorrhi- 
zal fungi data on experimentation with these spp. in nursery conditions is highly 
desirable. 

Species with wider host-specificity offer greater opportunity to evaluate their 
potential of forming symbiotic association with different host species in nurserv 
conditions and their subsequent survival and establishment at the site of planting. 

From the foregoing account it is apparent that mycorrhizal symbiosis is more 
pronounced and varied in the temperate zone. 

REFERENCES 
Marks, C. G., Kozlowski, T. T. 19"3. Ectomycorrhizae-their ecology and Physiology, New York, 

Academic Press, pp. 444. 
Mikola, P. 1970. Mycorrhizal inoculation in afforestation. Int. Rev. For. Res. 3 : 123-196. 
Trappe, J. M., Fogel, R. D. 1977. Ecosystematic functions of Mycorrhizae. In : The Below 
Ground System. Range Sci. Dep. Sci. 26 : 205-214. 

[ 15 ] 



Survey of native VAM fungi of saline soils of Haryana State 

H. S. THAPAR AND KAMLA UNIYAL 

Division of Forest Protection, 

Forest Research Institute, Dehra Dun 

Members of Endogonaceae are distributed widely in agriculture and forest soils 
throughout the world. However, no effort seems to have been directed to isolate and 
identify the VAM fungi inhabiting wastelands, degraded soils and soils of high 
salinity. Isolation, and multiplication of salinity tolerant efficient strains of VAM 
fungi is important for mass inoculum production and for tailoring roots of tree seed- 
lings suitable for rehabilitation and reclamation of these soils. With this objective, a 
survey was conducted to isolate and identify genera and species of Endogonaceae 
which form a normal component of soil microflora in saline soils of Haryana State 
under barren aud vegetation conditions. 

Soil samples were collected from Revar rectangle 74, Saraswati Range, 
Kurukshetra Forest Division and Kawani, Dhandh, Kirdhan and Bhanawali Pancha- 
yat areas of Hisar Forest Division. The soils at Saraswati are silty loam, hard and 
deficient in organic matter. The soil pH ranges between 9 to 10 at Saraswati and 
7.5-8.1 at Hisar. Due to their poor physical condition and adverse chemical 
composition the forest cover is normally very scanty or entirely absent. Among the 
different species tried in the past, Acacia nilotica, Albizia procera and Prosopis juliflora 
are able to survive and grow on such lands. 

Soil samples were collected randomly from 30 cm. deep pits from different 
locations of trials plots (150 m 2 ) laid down by F. R. I. at Saraswati covering a total 
area of 70,000 m a . The area was planted during July, 87 with 10 different hard wood 
species. The soil was collected by scraping vertically from top to the bottom of the 
pit and thoroughly mixed to form a composite sample. Five hundred gm. soil from 
each sample in 5 different lots of 100 g each was assayed by wet sieving and decanting 
technique (Gerdemann and Nicolson, 1963) and flotation method (Ohms, 1957) 
to collect spores and sporocarps of VAM fungi. The spores were cleared and 
mounted in lectophenol and examined under low and high magnifications. 

In all 10 species of Endogonaceous fungi were isolated of which 7 belong to 
Glomus, one to Gigaspora and two to Sclerocystis as listed below : 

1. Glomus caladonius (Nicol. and Gead.) Trappe and Gord. 

2. G. albidum Walker and Rhodes 

[ 16 ] 



3. G. fasciculatus (Thex.) Gerd. and Trappe 

4. G. macrocarpus Tul. and Tul. 

5. G. microcarpus Tul. and Tul. 

6. G. multicaulis Gerd. and Bakshi 

7. G. reticulatus Bhattacharjee and Mukerji 

8. Gigaspora nigra Nicolson and Schenck 

9. Sclerocystis coremoides Berk, and Broome. 
10. Sclerocystis sinuosa Gerd. and Bakshi 

The frequency of VAM fungi varied qualitatively in different locations and 
under different vegetation cover. Glomus spp. were most common of which Glomus 
macrocarpus was most abundant in the study sites distantly located from each other. 
Next to Glomus spp. Sclerocystis coremoides was common whereas Gigaspora sp. 
occurred, rarely. The lowest frequency was of Gigaspora spp. followed by G. reticu- 
latus, G. multicaulis and G. fasiculatus. According to Mosse (1973) Gigaspora 
and Acaulospora are more tolerant to acidity whereas Glomus spp. favour 
neutral and alkaline soils. The difference in species may be attributed to adaphic 
factors and host plant interactions at the particular site. Higher spore frequencies 
under Acacia {A. nilotica), Prosopis (P. juliflora) and Delbergia {D. sissoo) may be due 
to high crop density, pure composition of tree crop, age and host species compatibitity 
with VAM fungi. 

REFERENCES 

Gerdemann, J. W , Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted from 
soil by wet sieving and decanting method. Trans. Brit, mycol. Soc. 46 : 235-244. 

Mosse, B. 1973. Advances in the study of vesicular-arbuscular mycorrhiza. Ann. Rev. Phytopatho- 
logy 11 : 171-196. 

Ohms, R. E. 1957. A flotation method for collecting spores of a phycomycotons mycorrhizal 
parasite from soil. Phytopathology 47 : 751-752. 



[ 17 ] 



Impact of season on the distribution of VAM fungi associated 
with sesame 

T. SULOCHANA* AND C. MANOHARACHARY+ 

In India, fat and edible oils are mostly derived from oilseed crops like ground- 
nut, sunflower and sesame. Most of these crops are grown in phosphorus-deficient 
soils which are also usually deficient in other nutrients including moisture in varying 
degrees. The need to improve the efficiency of oilseed production is therefore obvious. 
In this context, the role of vesicular-arbuscular mycorrhizal fungi is receiving great 
attention in recent times in view of their beneficial effects on plant growth. The 
information on VAM association with sesame is scanty (Vijayalakshmi and Rao, 
1988). Recently an exhaustive range of studies has been carried out on VAM in 
relation to sesame (Sulochana, 1989). 

VA mycorrhizae are ubiquitous. They are present in the soil in the form ot 
chlamydospores, zygospores and azygospores, VAM symbiosis directly helps in the 
uptake of phosphorus and other nutrients (Mosse, 1981). However, seasonal 
variations can have a remarkable influence on the occurrence of the VAM spores 
(Nicolson and Johnston, 1979). Environmental conditions, besides the host plant, 
have significant effects on the distribution, density and composition of V A mycorrhizae 
(Daniels and Trappe, 1980). 

The occurrence and number of VAM fungal propagules in the rhizosphere 
soils supporting six cultivars of Sesamum indicum L. in kharif and rabi seasons of two 
years have been worked out. Altogether eleven VAM fungi belonging to Acaulospora, 
Glomus and Gigaspora genera were found associated in both the seasons. Out of the 
six cultivars tested, Gowri cultivar showed maximum VAM association in rabi 
as well as kharif seasons. 

VAM propagule number varied considerably among individual species and all 
the cultivars have shown at least five VAM species during their growth period. The 
quantitative data clearly indicate that, in all the seasons studied, the Gowri cultivar, 
followed by T-4 and E-8 were the best colonized and the propagule number was in 
direct correlation with the age of the crop plant. Among the VAM fungal species 
isolated, Gigaspora margarita, Glomus fasciculatum, G. epigeaum, G. constrictum and 

♦Department of Botany, Kasturba College for Women, Secunderabad-500026 

+Mycology & Plant Pathology Lab, Department of Botany, Osmania University, Hyderabad-500007 

[ 18 ]' 



G. monosparum are of predominant occurrence over others. Characteristically, Gowri 
cultivar was found harbouring all the eleven VAM fungal species in rabi and kharif 



The VAM propagule number was more in the rhizosphere soils of kharif crop 
than in rabi crop. The kharif season experiences good precipitation, moisture, 
average temperature and requisite quantities of nutrients. Accordingly the cultivars 
of sesame were found colonized heavily by VAM fungi both quantitatively and 
qualitatively in the kharif crop. 

REFERENCES 

Daniels, B. A , Trappe, J. M. 1980. Factors affecting spore germination of the vesicular-arbuscular 

mycorrhizal fungus Glomus epigaeus. Mycolagia 72 : 457-471. 
Mosse, B. 1981. Vesicular-arbuscular mycorrhiza research for tropical agriculture. Research 

Bulletin 194 : 5-81. 
Nicolson, T. H., Johnston, C. 1979. Mycorrhiza in the Graminae. II. Glomus fasciculaius as the 

endophyte of pioneer grasses in maritime sand dunes. Trans. Brit. Mycol. Soc. 72 ; 

261-268. 
Sulochana, T. 1989. Studies on vesicular-arbuscular mycorrhizal fungi in relation to the 

growth of Sesamum indicum L. Pli.D. Thesis, under approval, Osmania University, 

Hyderabad-500007, India. 
Vijayalakshmi, M., Rao, A- S. 1988. Vesicular-arbuscular mycorrhizal associations of sesame. 

Proc. Indian Acad. Sci. (Plant Sci.). 98 : (1) 55-59. 



[19 ] 



Density of vesicular arbuscular mycorrhizal fungi in different crops 
grown under black soil 

P. C. HIREMATH, K. M. HARINI KUMAR AND C. V. PATIL 
College of Agriculture, Raichur 

The group of fungi that form vesicular-arbuscular (VA) mycorrhiza are among 
the most common soil fungi and probably colonize more plant tissue than any other 
fungal group. They significantly benefit the crop in better nutrition. Native 
population of VA mycorrhizal fungi may or may not be effective in stimulating the 
growth of a crop in a particular soil. The relationship between VA mycorrhizal 
fungi and chemical factors have been studied little in tropical soils. 

VA mycorrhizae occur in almost all perennial crops of economic importance in 
the tropics. Wide variations in the VAM infections of trees growing under dry 
conditions (Diem et ah, 1981). Very little information is available regarding the 
effect of different crops on native mycorrhizal propagules in tropical black soils. The 
present survey was done to know VA mycorrhizal population density in tropical 
black soils under different crop stands. 

Soil and root samples collected from three Agricultural Research Stations 
(ARS) located at Hagari, Siruguppa and Gulbarga were analysed for population of 
VA mycorrhizal fungi. The soils have a pH of 7.8 to 8.5 and are low in nitrogen 
and available phosphorus, but fairly adequate in available potassium. Fifteen soil 
and root samples were collected from rhizosphere of each plant stand. Percentage 
mycorrhizal colonization in the root was assessed after staining with tryphan blue 
(Phillips and Hayman, 1970). Extra matrical chlamydospores in 100 g soil were 
determined by wet seiving and decantation procedure as outlined by Gerdemann and 
Nicolson (1963). The predominent spores were identified using the synoptic keys 
as outlined by Trappe (1982). 

The soils of ARS, Hagari are of two types. Majority of the area consists of 
black soils with clay to sandy clay in texture. Sand dunes are formed near the river 
bank, neem trees have been grown to stabilize the sand dunes. The major crops grown 
in black soils are : rabi sorghum (Sorghum vulgare); safflower (Carthemus tinctorius); 
wheat (Triticum aestivum) and cotton (Gossypium hirsutum). Some plantation crops 
like guava {Psidium guayava), mulberry (Morus alba) and subabul (Leucana leucoce- 
phaula) are also grown in black soils. Neem and guava are the main plantations in 
sand dues and sandy loam soils. The per cent root colonization of VA mycorrhizal 

[ 20 ] 



fungus varied from 18 to 20 and spore number from 170 to 175 per 100 g soil. 
Among the field crops tested, safflower recorded the highest root colonization (30%) 
and spore number (320/100 g soil) where as, the lowest spore count was observed 
under plantation trees and the per cent root colonization in sorghum crop. The 
spore population in Newzeland soil varied from 6 to 1590 with an average spore 
number of 196 per 100 g of black soil. 

The soils of ARS, Siruguppa are deep black (vertisol) with silty clay texture. 
The major crops grown are wheat, maize (Zea mays), groundnut (Arachis hypogaea), 
cotton and safflower under protective irrigation. The per cent root colonization 
varied from 10 to 28 and spore number from 78 to 290 per 100 g soil. Highest per cent 
root colonization and spore count was observed in safF/ower and the lowest in maize. 

The soils of ARS, Gulbarga consisted of black soil with clay texture. Sorghum . 
and redgram (Cajanus cajari) are the major crops grown in this region. The per cent 
root colonization of VA mycorrhizal fungus varied from 6 to 10 and spore count 
from 76 to 80 per 100 g soil. 

The predominent VA mycorrhizal fungal spores isolated from black soils 
belonged to genus Glomus. The spores isolated from the soils of arid and semi-arid 
region belonged to three genera viz., Glomus, Gigaspora and Sclerocystis. 

The native VA mycorrhizal population was less in black soil (vertisol) as 
compared to red soil (alfisol). The black soils with sandy loam texture exhibited 
higher mycorrhizal activity than those with clay texture. The clay content in soil was 
also found to influence the VA mycorrhizal population. The host plant also influen- 
ced the VA mycorrhizal population. The highest mycorrhizal population was noticed 
associated with safflower, while the lowest was with sorghum. Wheat, maize, 
groundnut, cotton and redgram had intermediate population. The distribution of 
VA mycorrhizal population in black soils was mainly dependent on soil properties 
and mycorrhizal dependancy^of host plant. 

REFERENCES 

Diem, H. G , Gueye, I., Gjanmazzi-Pearson, V., Fortin, J. A., Dommergues, Y. R. 1981. Ecology 

of VA mycorrhizae in the tropics : the semi-arid zone of Senegal. Acta Ocecologica 

Oecol. Plant. 2 : 5J-62. 
Gerdemann, J. M„ Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-240. 
Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing roots and staining parasitic 

and vesicular arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Brit. 

Mycol. Soc. 55 : 158-161. 
Trappe, J. M. 1982. Synoptic keys to the genera and species of zygomycetous mycorrhizal fungi. 

Phytopathology 72 ; 1102-1108. 



C 21 ] 



Mycorrhizal investigations in some orchids 

P. KAUSHIK, S. K. SHARMA AND S. KUMAR 

Department of Botany, 

G. K. University, Hardwar-249 404 

Wahrlich(1986) reported 500 orchid species which show fungi inside their 
roots. Present study was made to investigate the mycorrhiza] association in the four 
genera i. e. Epipactis, Calanthe, Aerides and Vanda. The former two are terrestrial 
and latter two are epiphytic. All genera bear mycorrhizal associations with their 
roots of different intensity depending upon the different environmental conditions. 
Bernard (1909) considerd mycorrhiza as parasitic interaction in orchids. Rayner (1926) 
suggested that, mycorrhiza are beneficial to host plant due to the absorption of 
mineral nutrients from the soil. 

A number of authors have studied nature, mode of infection and penetration 
of the mycorrhizal fungus into the host. Parasitic pathogenic nature of mycorrhiza 
and relation of mycorrhizal fungi was studied by Curtis (1939). 

In all four taxa mycorrhizal endophyte was found to be present in the roots. 
In the middle zone of root cortex more intensity of peletons was found in comparison 
to epidermal or central V. B. region. In case of epiphytic orchids as Aerides multi- 
flora and Vanda Cristata the infection mostly takes place at the base of the attachment 
of the root to the substratum while in terrestrial taxa as Calanthe plantagineae and 
Vanda parviflora it appears all around in the cortical region. 

The size of peletons was also measured and found that infection was more in 
Epipactis latifolia (64-176 um) in comparision to Calanthe plantagineae (16-19 um) in 
terrestrials while in case of epiphytic taxa infection was more i.e. 40-110 um in 
Aerides multiflora in comparision to Vanda cristata (17-22 um). 

Penetration of hypha were observed through the epiblamal cells while in 
terrestrial taxa entry of fungus was observed through root hairs. 

The fungal endophyte of the above mentioned four orchid species were 
isolated and identified on the basis of their growth character, size of hypha, spore 
cells etc. The isolated mycorrhizal species are : 

1. Rhizotonia sps. :- Mycelium branched, moniliform hyphae, brownish in 
colour, 3-3.5 um. Sexual reproductive bodies are hot formed. 

Isolated from — Epipactis latifolia 

t 22 ] 



2. Rhizotonia dichotoma :- Mycelium branched, white, septate, moniliform. 
Vegetative hyphae of much elongated cylindrical ceils 120—176x6—8 urn. Spore 
cells are very few in number ranging 32—48x9.6—12.8 um. 

Isolated from— Calanthe plantagineae 

3. Rhizotonia repens :- Mycelium white differentiated into main and aerial 
hyphae which are elongated ranging from 6-8 um. Sexual reproductive bodies/ 
sporodochia were not observed. 

Isolated from- -Aerides multiflora 

4. Rhizotonia dichotoma :- Mycelium white, elongated, brached with septate 
hypha, 5-6 um thin of intertwined moniliform cells 18-20 umx7-ll um in size. 
Sexual reproductive bodies were not observed. 

Isolated from— Vanda cristata 

REFERENCES 

Bernard, N. 1909. Rese arches experimentales our les Orchidees. Rev. Gen. de Bot. 16:405-451. 
Curtis, T. 1939. The relation of specificity of orchid Mycorrhizal fungi to the problem of symbiosis. 

Amm, J. Bot. 26 : 390-398. 
Rayner, M. C. 1926. Mycorrhiza. Newphytol. 25 : 1-50. 
Wahrlich, W. 1986- Beitrage Zur Kenntris der Orchideen Wurzelpilze. Bot. Zeit. 44 : 480-487. 



[ 23 ] 



Incidence of vesicular arbuscular mycorrhizal fungi in Raipur soils 

NIBHA GUPTA AND S. S. ALI 

Department Bioscience, , 

Ravishankar University, Raipur-492 010 

Occurrence of the symbiotic VAM fungi has been reported in soils of several 
places in India. It is now well known that these organisms are ubiquitous in 
distribution and perform important roles in uptake of phosphorus, sulphur, water and 
other ions for their macrosymbiont host plants, besides being a source of nutrition in 
certain cases. The functional attributes of VAM fungi assign them a great priority 
in modern researches in microbial biotechnology. This study is an outcome of such 
a consideration that has been initiated in Chhattisgarh region of M.P. for the first 
time ever. 

The isolation of VAM spores (Gerdemann and Nicolson, 1983) from these 
soils has shown incidence of eight species of Glomus and only one of Sclerocystis. 
Glomus fasciculatus, G. mosseae and G. macrocarpum were distributed widely here, 
with almost an equally wide incidence of Glomus sp. I. However, G. reticulatum, G. 
constrictum, G. monosporus, Glomus sp. 2 and Sclerocystis rubricolla were restricted in 
their distribution only to certain soil samples. It appeared that in the occurrence of 
the latter species, the host plant distribution had some relationship. The unidentified 
species of Glomus appear to be undescribed in the literature so far. 

Root association of VAM (Phillips and Hayman,I970)hasso far been recorded 
in 19 plants belonging to 10 families that grow here. In the plants of Leguminaceae 
and Euphorbiaceae root colonization was relatively better in respect of mycelial 
and vesicular growth. VAM association found in Amaranthus spinosus and Eclipta 
alba was recorded in this study. Gerdemann, (1968) has reported that the family 
Amaranthaceae is non-mycorrhizal. Similarly, Eclipta alba has been considered 
non-mycorrhizal (Manoharachary et ah, 1987). It suggests that the mycorrhizal 
associations might be governed by microhabitat conditions. 

REFERENCES 
Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal endogone species extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. soc. 46 (2) : 235-244. 
Gerdemann, J. W, 1968. Vesicular-arbuscular-mycorrhizae and plant growth. Annual Review of 

Phytopathology 6 : 397-418. 
Manoharachary, C, Ramarao, P., Sulochana, T. 1987. Preliminary survey of VAM fungi in some 

weeds. In : Proceedings of National Workshop on mycorrhizae. J. N. U. Delhi, pp. 

288-289. 
Phillips, J. M.,Hayman,D. S. 1970. Improved procedure for clearing root and staining parasitic 

and VAM fungi for rapid assessment of infection. Trans. Brit. Mycol. Soc. 55 : 158-161. 

[ 24 ] 



Mycorrhizal reproduction as influenced by moisture stress 

GOKULDAS PAI, D. J. BAGYARAJ AND T. G. PRASAD 
Departments of Agricultural Microbiology and Crop Physiology, 
University of Agricultural Sciences, GKVK, Bangalore-560 065 

The effect of changing water availability on the vesicular arbuscular (VA) myco- 
rrhizal fungi has been sorely ignored barring few stray reports. Manson (1964) pointed 
out that Endogone spore numbers in soils increased after mild and dry winter than cold 
and wet winter. Redhead (1975) reported that the amount of water which was 
optimal for the growth of plant also resulted in the greatest production of fungal 
Spores. Nelson and Safir (1982) reported that drought stress reduced spore product- 
ion by Glomus fasciculatum. Bethlenfalvay et al, (1988) reported that colonization 
of soybean roots by Glomus mosseae did not vary with stress but the biomass and 
length of extracellular mycelium was greater in severely stressed than non-stressed 
plants. The present experiment was conducted to understand the effect of moisture 
stress on mycorrhizal root colonization, and production of spore and infective 
propagule numbers by Glomus fasciculatum. 

Cowpea plants were grown with G. fasciculatum inoculum in sterilised and 
unsterilised soil with different levels of moisture stress imposed after 6 weeks of 
sowing viz. i) No stress-A) watering daily to field capacity (FC). ii) Mild stress-B) 
watering once in 3 days to FC. C) Maintained continuously at 75% FC. iii) Severe 
stress - D) watering once in 5 days to FC - E) Maintained continuously at 50% FC. 
Observations on plant biomass, root dry weight, per cent mycorrhizal root coloni- 
zation, spore numbers and infective propagule numbers were recorded after 3 weeks 
of imposing treatments. 

Maximum plant biomass was recorded in plants watered daily to FC. Root 
growth was reduced markedly by increased moisture stress. In sterilised soil the per 
cent mycorrhizal root colonization ranged from 73.6 to 78.8 while in unsterilised soil 
it ranged from 72.4 to 80.4. Maximum mycorrhizal colonization was observed under 
severe stress where plants were watered once in 5 days to FC. 

The number of spores and infective propagules were highest in pots watered 
daily to FC and least in pots maintained continuously at 50% FC. But the per cent 
reduction in spore numbers was always more than the per cent reduction in the 
number of infective propagules suggesting that there is more hyphal growth and less 

[25 ] 



sporulation during moisture stress. The milder and severely stressed pots which were 
watered back to FC (Treatments B and D respectively) had more number of spores 
and infective propagules than the pots maintained continuously under similar stresses 
(Treatment C and E respectively). Under similar stress condition, the number of 
spores and infective propagules were more in unsterilised soil than the sterilised soil. 

Severe stress condition of watering once in 5 days to FC encouraged mycorrhi- 
zal root colonization, while the severe stress condition of maintaining pots continuously 
at 50% FC suppressed the number of spores and infective propagules. Watering to 
FC once in 3 or 5 days favoured sporulation better than maintaining pots continuously 
at 50 or 75% FC. 

REFERENCES 

Bethlenfalvay, G. T., Brown, H. S., Ames, R. N., Thomas, K. S. 1988. Effect of drought on host 
and endophyle development in mycorrhizal soybeans in relation to water use and 
phosphate uptake. Physiol. Plant. 72 : 565-571. 

Manson, D. T. 1964. A survey of numbers of Endogone spores in soils cropped with barley, 
raspberry and strawberry. Hort. Res. 4 : 99-103. 

Nelson, C. E., Safir, G. R. 1982. Increased drought resistance of myccrrhizal onion plants caused 
by improved phosphorus nutrition. Planta 154 : 407-413. 

Redhead, J. F. 1975. Endotrophic mycorrhizas in Nigeria : Some aspects of the ecology of the 
endotrophic mycorrhizal association of Khaya grandifolia C. DC. In : Emdomycorrhizas, 
Eds. F. E. Sanders, B. Mosse, P. B. Tinker, New York, Academic Press, pp. 447-460. 



I 26 J 



Studies on the mycorrhiza of Apple (Malm domestica borkh.) 

MEERA THAKUR AND T. N. LAKHANPAL 
Department of BioSciences, Himachal Pradesh University, Shimia, (H. P )-I7l005 

No work on the mycorrhiza of apple plants has been done so far in any part 
of India. The present studies are the first on characterization and identification of 
mycorrhiza and on the mycorrhizosphere of Royle delicious var. of apple plants. 

Soil samples of apple plant of different ages ( 1 yr, 2 yr, 3 yr, 4yr and mature 
fruit bearing plants) were taken at monthly intervals beginning with December 1988 
to May 1989. 

For characterizing the mycorrhizal types, morpho anatomical studies were 
conducted following Zak (1971) and for ascertaining the VAM infection, the whole 
roots were stained with trypan blue as given by Philips and Hayman (1970). For 
isolating VAM from soil samples, wet sieving and decanting method of Gerdemann 
and Nicolson (1963) was followed. 

For isolation of fungi from the mycorrhizosphere, the dilution plate method 
(Waksman, 1927) was employed. Martin's Czapekdox and Potato Dextrose Agar 
medium were used for raising cultures. The petriplates were incubated at22±2 c C 
and examined at regular intervals. 

Moisture content and pH of soil was recorded by standard procedures. The 
mycorrhizal root activity was measured following Hervey et al. (1976). 

Mycorrhizal roots were observed to be without any surrounding fungal hyphae 
or rhizomorphs but their tips were swollen near the apices. These roots were creamish 
white in colour. 

The mycorrhizal roots showed a typical ectoendomycorrhizal anatomy. The 
sections showed both inter and intracellular infection. T. S. of 1 yr old roots showed 
hyphal penetration in the entire cortex region surrounded by Hartig net but the stelar 
portion had little infection and the pith region had no infection at all. Sections of 
two yr old roots showed in addition vesicle like structure in the cortical cells, and the 
hyphal infection extended up to stelar portion but pith was still without infection. 
Three yr old plants showed infection in the stelar and pith region as well. Four yr old 
plants showed variable development of the Hartig net. The hyphal penetration was both 
inter and intracellular. The whole cortical region was infected and each cortical showed 
the presence of many vesicle^ per cell compared to the 2-4 per cell vesicles in 1-3 yr 

[ 27 ] 



old plants. The sections from mature tree bearing fruits showed heavy vesicular 
infection of endomycorrhiza in the cortex, stele and pith region, each cell having 
many vesicles per cell. Because of secondary growth, the primary cortex and hence 
the Hartig net was greatly reduced. Instead the cork cells formed a definitive layer. 

In the younger plant roots the Hartig net was well developed and easily discernible 
conforming to ectoendomycorrhizal type, while in older plant roots, Hartig net was 
not clearly visible due to the secondary growth. The VAM infection was confirmed 
by the presence of large number of hyphae running in the cortical and stelar portion, 
and these hyphae forming vesicles. Finger like projections or arbuscules were also 
observed arising, from the hyphae, confirming hypal and vesicular infection of VAM. 

In the studies on mycorrhizosphere, twenty species of fungi, 4 belonging to 
zygomycotina, 16 to Deuteromycotina and one form of sterile mycelium have been 
isolated from the mycorrhizosphere. Aspergillus niger and A . fumigatus were most 
predominant and the frequency distribution of A. niger, A. fumigatus and Mucor 
heimalis was recorded to be higher than the other fungi isolated. Rhizopus nigricans 
exhibited abundant growth in the months of January, March, April and May; 
Fusarium moniliforme in the months of December, January, March, April and May; 

F. oxysporum in December, January and March. Trichoderma sp. was found only 
in the month of December, Curvularia lunata in March and Phoma sp. was abundant 
in April and May. Alternaria alternata in December, January and February; Mucor 
sp. in the months of January, March and May and Rhizopus sp. in February and 
March. Sterile mycelial form was recorded in all the six samplings but was more 
predominant in the months of March, April and May. 

VAM studies showed six fungal spore types, i. e. Glomus mosseae G. candidus, 

G. fasciculatum, G. macrosporum, Endogone increseta and Gigaspora sp. Unidentified 
perithecia of an ascomycete were also present in abundance in all the soil samples. 
The root activity was observed to be less in December, January and February and 
more in April and May. 

REFERENCES 

Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizae Endogone spscies extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-244. 
Hervey, A. E., Larsen, M. J., Jurgensen, M. F. 1976. Distribution of ectomycorrhizae in a mature 

Douglas-fir/larch forest soil in Western Montana. For. Sci. 22 : 393-398. 
Philips, J. M., and Hayman, D. S. 1970. Improved procedure for clearing roots and staining 

parasitic and Vesicular arbuscular mycorrhizal fungi for rapid assessment of infection. 

Trans. Brit. Mycol. Soc. 55 : 158-161. 
Waksman, S. A. 1927. Principles of soil microbiology. London : Bailleire, Tindall and Coxland. 
Zak, B. 1971. Characterization and identification of Douglas fir mycorrhizae. In : Mycorrhizae. 

Ed. E. Hacskaylo, Washington, USD A Misc PubL 1189, pp. 38-58. 



[' 28" ] 



Occurrence and distribution of vesicular-arbuscular mycorrhizal 
fungi in acid soils of North Eastern India 

M. N. VENKATARAMANAN, RUMI KOTOKY AND H, D SINGH 

Division of Biochemistry, Regional Research Laboratory, 

Jorhat-785006, Assam, India 

The intrinsic interest in the study of vesicular-arbuscular mycorrhizal fungi is 
due to their beneficial role in the growth of the plants. Prior to exploiting the 
biofertilizer potential of these organisms, it is necessary to examine the occurrence 
and distribution of the VA mycorrhizal fungi in soils. Although several studies hove 
been conducted in other parts of the country on these fungi (Bagyaraj et ah, 1979), 
their distribution in the soils of N.E. India has not been studied. The qualitative 
and quantitative distribution of the VA mycorrhizal spores in soils of North 
Estern India are described. 

Soil samples from different areas in Assam, Arunachal Pradesh, Manipur, 
Mizoram and Nagaland were collected, air dried and sieved through 2.0 mm mesh 
to remove coarse debris and root bits. Each soil sample was thoroughly mixed 
before examining them for spores. For measurment of pH, soil was mixed with two 
volumes of distilled water, stirred for 30 minutes and the supernatant was collected. 
For isolating spores, lOOg soil of each sample was stirred in excess quantity of water 
and decanted into sieves (Gerdemann and Nicolson, 1963). The fractions collected 
between 300-90 /«n mesh were examined for spores. Four replicates were scresned 
for each sample. 

VA mycorrhizal spores were abundant in samples of Assam as compared to 
those of hilly regions viz. Arunachal Pradesh, Kohima, Nagaland, Manipur, 
Mizoram. Highest number of spores was recorded in samples from Golaghat 
followed by Titabor, Jorhat and Halflong in Assam. The VA mycorrhizal spores 
were present in all the samples except that from Mizoram. The low count in hill 
land samples may be due to factors like soil erosion or poor vegetational cover. 

Scutellospora nigra (Gigaspora nigra) Walkers and Sanders Comb. nov. Sclero- 
cystis rubiformis, Glomus macrocarpus were commonly found in plain soils of Assam. 
Other species infrequently isolated were Gigaspora decipiens, Hall and Abbot, Glomus 
heterosporum Smith and Schenck and Glomus leptotichum, Schenck and Smith. In hilly 
regions large spore types were absent but screenings from 150-90 jim consistently 
revealed individual spores of Glomus sp. A hitherto undescribed species of Gigaspora 

E 29 ] 



was isolated from several areas in and around Jorhat. The spores occurred singly in 
soil which were globose or ellipsoidal. Older spores were dark brown to black with pale 
brown suspensor cell attached to the base of the cell. Spore wall with multiple 
layers was dark brown to black with separable inner hyaline wall layer. Accessory 
vesicles were borne on coiled hyphae they had yellow outer wall, smooth vesicles 
(6-8, 33.2 /tm in diam). The new species has been tentatively named as Gigaspora 
echinulata. 

Spores provide a reliable index to the existence of these fungi in a particular 
soil. They do not give an absolute index to the infectivity of soil because spore 
forming capacity varies from species to species and is an inherent species characteri- 
stic (Gerdemann, 1975). Nevertheless the preponderance of VA mycorrhizal spores 
in plains as compared to those in hilly areas indicate that hill land soil will be more 
amenable and responsive to VAM fungal inoculation trials. As VA mycorrhizal 
fungi have wide host range in native soils where their prevalence is more, these native 
fungi are likely to mask the efficiency of the inoculant fungi. This would render 
inoculation trials with VA mycorrhizal fungi difficult and unsatisfactory. It is felt that 
in hill land soils the persistency of the species diversity among VA mycorrhizal fungi is 
a field of investigation which needs to be evaluated before any meaningful field trials 
could be conducted. From the study it appears that in hilly areas, inoculation trials 
with VAM fungi will be successful in highly susceptible crops like chillies, soybean 
and maize. 

REFERENCES 

Bagyraj, D. J., Manjunath, A. K., Patil, R. B. 1979. Interaction between a vesicnlar arbuscular 
mycorrhiza and Rhizobium : their effect on soybean in the field. New. Phytol. 82 : 141-145. 

Gerdemann, J. W., Nicolson, J. H. 1963. Spores of mycorrhizal Endogone species extracted from 
soil by wet sieving and decanting. Trans. Brit, mycol Soc. 46 : 235-244. 

Gerdemann, J. W. 1975. Vesicular arbuscular mycorrhizae. In : The development and function of 
Roots. Eds. J. G. Torrey, D.I. Clarkson, Academic Press, London. 



[ 30 ;| 



Preliminary survey of mycorrhizal fungi in some weeds and 
cultivated plants in Meerut 

SANJAY KUMAR RATHI AND LOKENDRA SINGH 
Department of Botany, Meerut College, Meerut-250006 

VAM fungi are usually associated with most plants and are important in 
agriculture, horticulture and forestry. VAM are obligate symbionts formed by 
nonseptate phycomycetous fungi belonging to the genera Glomus, Gigaspora, 
Acaulospora, Sclerocystis and Endogone, in the family Endogonaceae of the order 
Mucorales. Endotrophjc VA Mycarrhizae are well known to increase nutrient uptake, 
resistance to drought and salinity and tolerance to pathogens. They seem to have 
a potential as biofertilizers (Jalali, 1989). The limited Indian work on VAM reviewed 
by Bagyaraj (1986), showed that the hosts plants can influence the qualitative and 
quantitative nature of the spores of VAM fungi. If this is so, weeds growing on 
fallow agricultural lands would greatly influence the activities of VAM fungi and the 
health of the crops grown on such lands. As VAM fungi associated with weeds have 
been surveyed by few workers from Delhi, Allahabad, Hyderabad and Jorhat and no 
such work has been undertaken in Meerut area, the present investigation was 
taken up. 

One cm root segments of plants under reference were cleared in 10% KOH 
solution and stained in cotton blue. Under the light microscope characteristic fungal 
structures were seen. The data are presented in Table 1. 

Table 1. Mycorrhizal association of weeds and cultivated plants. 

Host Mycorrhizal Association 



1. 


Abutilon indicum 


2. 


Achyranthes aspera 


3. 


Ageratum conyzoides 


4. 


Argemone maxicana 


5. 


Cassia glauca 


6. 


.Cassia occidentals 


7. 


Cassia sophera 


8. 


Cannabis sativd 



[ 31 } 



Host Mycorrhizal Association 

9. Croton bonplandianum — 

10. Convolvulus arvensis + 

1 1 . Convolvulus pluricaulis + 

12. Commelina benghalensis -f , 

13. Eclipta alba — 

14. Euphorbia hirta -j- 

15. Euphorbia mkrophyla -f- 

16. Euphorbia thymifolia — 

17. Heliotwpium indicum -j- 

18. Justkia gendusassa — 

19. Nicotiana plumbaginifolia -f- 

20. Parthenium hysterophorus -f- 

21. Peristrophe bkalyculata -j- 

22. Phyllmthus niruri + 

23. Peperomia pellucide -f- 

24. Portulaca grandiflota — 

25. Sida cordifolia + 

26. Xanthium strumarium + 

27. Catharanthus roseus + 

28. Dalbergia sissoo -j- 

29. /■/cms krishnae + 

30. G/nfcgo 6//ofo — 
+ = Present, — = Absent 

Maximum percentage infection in decreasing order was found in Peperomia 

pellucide (66.1%), Abutilon indicum (63.7%), Euphorbia hirta (58.0%), Nicotiana 

plumbaginifolia (56.5%), Argemona mexicana (51.5%), which was followed by 
Parthenium and Phyllanthus. 

REFERENCES 
Bagyaraj, D. J. 1986. Current status of Mycorrhiza research in India. In : Amelioration of soil 

by trees. Eds. R. T. Prinstey, M. J. Swift, Commonwealth Sciences Council, London, 

pp. 95-102- 
Jalali, B. L 1989. Interaction between VA Mycorrhiza and plant pathogens. Mycorrhiza News 

1 (2) : 1-2; 

t 32 J 



Extraction of vesicular-arbuscular mycorrhizae spores and effect of 
fertilizers on their population in oilseeds cropped soils 

B. N. SHUKLA AND N. VANJARE 
Department of Plant Pathology, JNKVV, Jabalpur 

Several methods have been developed from time to time for extraction 
of vesicular-arbuscular mycorrhizae (VAM) spores from soil (Hayman, 1970; Sutton 
and Barron, 1972). The floatation and adhesion technique of Sutton and Barron 
(1972) is claimed to be the most efficient technique for recovery of VAM spores 
from soil. The present paper reports a modification of the technique and is most 
suitable for survey studies. 

Information pertaining to VAM associated with oilseed plants in Jabalpur is 
lacking. Qualitative and quantitative examination for distribution of major genera of 
VAM associated with oilseed crops was undertaken and the influence of fertilizers on 
VAM population was also investigated. 

The modified method is less time consuming as it takes only 15 minutes 
whereas the method of Sutton and Barron (1972) requires 2 hours. White polyster 
cloth with a pore size less than 10 /tm is most ideal for retention of all types of VAM 
spores. This cloth can be reused after washing and hence is economical. Further, 
separatory funnels are not required. Maximum spores can be mounred at a time 
and recovery on adhesive tape is excellent and the spores are clearly discernible. 

The effect of nitrogen on VAM population with regards to oilseed crops 
(Sesamum, Sunflower and Mustard) revealed a unique adverse effect of increasing 
levels of nitrogen. From the initial low level itself, the population decreased and 
continued gradually till zero at high levels indicating high sensitivity of VAM to 
increasing levels of nitrogen in oilseed cropped soils. 

A declining trend of VAM population with increase in phosphorus levels has 
been observed in Sesamum, Suflower and Mustard crops. High phosphorus levels 
in soil are deterimental for the symbiotic establishment of VAM with these 
oilseed roots. 

[ 33] • 



In oilseed crops, there is an adverse effect of potash as its level is increased. 
In oilseeds, it seems that there is inverse relationship between VAM spore population 
and potash level. 

In all soil samples analysed, only one genus i. e., Glomus spp. was 
encountered. 

REFERENCES 

Hayman, T>. S. 1970. Endogone spore numbers in soil and vesicular arbuscular mycorrhizae in 
wheal as influenced by season and soil treatment. Trans. Brit. Mycol. Soc. 54 : 53-63. 

Sutton, C. J., Barron, G. L. 1972. Population dynamics of Endogone spores in soil. Can. J. Bot. 
50 : 1904-1914. 



I 34 J 



Suitable source end level of nitrogen for mass production of the 
VA mycorrhizal fungus Glomus fasciculatum 

M. N. SREENIVASA AND D. J. BAGYARAJ 

Department of Agricultural Microbiology, University of Agricultural Sciences, 

Dharwad, India 

Vesicular-arbuscular mycorrhizal (VAM) fungi being obligate symbionts have 
not Been cultured on artificial media. Recent studies have shown that large scale 
production of VAM inoculum is technically feasible through pot culture using an 
appropriate host, substrate and nutrients. Nitrogen is one of the important 
nutrients required by plants for growth and development. Yet, the information 
available on the effect of different nitrogen sources on VA mycorrhiza is scanty. It 
appears that hightest concentration of nitrogen fertilizers will be inhibitory to VAM 
development. Some workers found, that ammonium source encourages VAM 
development compared to nitrate source (Davis and Young, 1985), while few others 
recorded the reverse to be true (Chambers et ah, 1979). When N-source was 
applied as 50% ammonium+50% nitrate, maximum root colonization was observed 
in careals (Thompson, 1986). The present investigation was undertaken to find out 
the best source and level of N for mass production of the VAM fungus, Glomus 
fasciculatum. 

Our earlier studies on mass production of G. fasciculatum brought out that 
Rhodes grass (Chloris gayana Kunth) and periits : soilrite mix (1:1 by volume) to be 
the best host and substrate respectively for mass production ofG. fasciculatum 
(Sreenivasa, 1986). Hence the same host and substrate were used in the present 
study. Three sources of N were used in the study : Nitrate as calcium nitrate with 
15.5% N, ammonium as urea with 45% N and ammonium nitrate as calcium 
ammonium nitrate with 20.5% N atO, 10, 20, 40, 80 and 120 ppm N. 

The mycorrhial parameters viz., percentage root colonization, extramatrical 
chlamydospore number and number of infective propagules per unit weight of 
inoculum increased upto 10 ppm N in both the sources. When N was used as 
a mixture of ammonium and nitrate, all the three mycorrhizal parameters increased 
with increase in N-level upto 80 ppm but decreased significantly at 120 ppm N level. 
The inoculum potential was maximum at 80 ppm N applied as ammonium nitrate 
which was the best level and source of N for mass production of G. fasciculatum. 
A significant increase in shoot and root dry weight was ecorded with increasing 
levels of N applied as any source except ammonium nitrate at 120 ppm N level. 
Maximum shoot and root biomass was recorded at 80 ppm N applied as 
ammonium nitrate. This suggests that the source and level of N supporting maxi- 

[ 35 ] 



mum mycorrhization also supports maximum plant growth. Thus the results of the 
present study clearly bring out that nitrogen applied as ammonium nitrate at 80 ppm 
N level, is the best for mass production of G. fasciculatum with maximum inoculum 
potential. 

REFERENCES 

Chambers, C. A., Smith, S. E., Smith, F. A. 1979. Effect of ammonium and nitrate ions on 

mycorrhizal infection, nodulation and growth of Trifoltum subterraneum. New Phytol. 

85 : 47-62. 
Davis, E. A., Young, J. L. 1985. Endomycorrhizal colonization of glasshouse grown wheat as 

influenced by fertilizer salts when banded or soil mixed. Can. J. Bot. 63 : 1 196-1203. 
Sreenivasa, M. N. 1986. Inoculum production of the Vesicular-arbuscular mycorrhizal fungus, 

Glomus fasciculatum. Ph.D; thesis, Univ.- Agril. Sci., Bangalore. 
Thompson, J. P. 1986. Soilless culture of vesicular arbuscular mycorrhizae of cereals : effects of 

nutrient concentration and nitrogen source. Can. J. Bot. 64 : 2282-2294. 



t 36 r 



Nutrient release from litter and the development of mycorrhizae 
in more disturbed and less disturbed forest communities 

S. KSHATTRIYA, D. K. JHA, G. D. SHARMA AND R. R. MISHRA 
Department of Botany, North-Eastern Hill University, Shillong 

Forest litter is a unique component of the forest biogeoneocoenosis and one 
of its major indicators of energy transfer. Equally significant is the role of forest 
litter in soil formation and its evolution. Litter fall and decomposition are important 
functional aspects of a forest ecosystem. The litter on the soil surface acts as an 
input-output system and is important in the nutrition of wood-lands, particularly of 
those on soils of low nutrient availability, where the trees rely to a great extent upon 
the efficient recycling of nutrients. 

Slash-burn agriculture, which is locally called as 'Jhum' is the predominant 
type of agriculture in North-Eastern India. In recent times, owing to population 
explosion and urbanization the jhum cycle has been reduced from a more favourable 
20-30 years to a short period of 5 years. It has adversely affected the yield, the soil 
environments in terms of physical structure, soil fertility and vegetation cover. 

The maintenance of soil fertility in hot, humid high rainfall area is a serious 
problem and is more severe when the jhum cycle becomes short. Heavy losses of 
carbon, nitrogen, phosphorus and sulphur occur due to volatilization during burn, 
perculation and runoff. This nutrient stress condition causes a variety of reproduc- 
tive and growth strategies in successional species. It is evident that majority of 
plants occuring in natural stressed environments are normally mycorrhizal (Reeves 
et a/., 1979). 

The aim of the study was to evaluate the probable reasons of disturbance on 
nutrients release and their effect on VAM development. The study was carried out 
at Byrnihat located in East Khasi Hills of Meghalaya at 26'ON latitude 95'0" 
longitude at an altitude of 100m MSL. The climate of the study area was hot and 
humid with an average rainfall of 220cm per annum. 

Decomposition of litter of different plant species showed a treat variation. 
The microbial degradation of the herbaceous woody litter on highly disturbed site 
was faster than the same in case of less disturbed ones. The release of nutrients like 
nitrogen and phosphorus also showed variations. Ageratum sp. a common weed 

t 37 ] 



harboured more nitrogen content than woody Mallotus sp. In both the cases 
nitrogen was more in the beginning and it decreased afterwords, which was again 
increased in the later part of decomposition. 

In case of less disturbed .forest stand, the rates of decomposition of Vitex and 
Holarohena sp. leaf litters were slow. These two species too had initial high nitrogen 
content, which decreased after that with the onset of decomposition. The least 
amount of nitrogen was detected in July. An increase in nitrogen content was 
observed again in the later part of decomposition. The phosphorous content of the 
leaf litter was more in the beginning which decreased in the following months. An 
increase in P-contents was observed in May and in later part of decomposition. 

The soil samples from less distrurbed site contained high nutrient concentration 
as compared to its more disturbed counterpart. During dry winter months the soil 
contained less nitrogen as compared to wet rainy months. The maximum available 
P was estimated more in May and less in winter months. 

The plant species growing in more degraded site had higher mycorrhizal 
infection than those in less disturbed site. No marked seasonality was observed in 
mycorrhizal infection. In general, there was heavy infection in spring and rainy 
months. The endogonaceous spore population was high in less disturbed site than 
in more disturbed one. Maximum spores were counted in winter months. 

From the results, in was evident that disturbance of forest stand has affected 
the mycorrhizal establishment. The less no. of endogonaceous spores in more 
disturbed site may be due to the high degree of disturbance which led to the reduction 
and possibly elimination of mycorrhizal propagules (Reeves et al., 1979). On the 
other hand, the high intensity of mycorrhizal infection was attributed to low nutrient 
status of soil. It seemed that under nutrient stressed condition and under favourable 
climatic conditions the mycorrhizal fungi spread better in the fast growing host 
species and formed chlamydospores in nutrtient rich and slow growing tree species. 
Infection was high in winter months when less N and P were estimated from soil, 
where as the low infection level in wet rainy months were positively correlated with 
moderate nutrient status of soil due to rapid release of nutrients from litter after 
increased microbial activity. The soil disturbance may affect P-mobilization due to 
effect on vesicular-arbuscular mycorrhizal infection (Fairchild and Miller, 1988). A 
rapid recovery in P-uptake and VAM infection with time may take place. The 
growth advantages attributed to VAM are believed to be associated with an increase 
in the nutritional status of plants brought about by increased P-uptake from degraded 
soil (Mosse, 1973) and water transport (Safir etal., 1972). 



t 3& ] 



REFERENCES 

Fairchild, G. L., Miller, M.H. 1988. Vesicular-arbuscular mycorrhizas and the soil disturbance- 
induced reduction of nutrient absorption in maize. II. Development of the effect. New 
Phytol. 11 : 75-84 

Mosse, B 1973. Advances in the study of vesicular-arbuscular mycorrhiza. Ann. Rev. Phytopathol. 
11 : 171-196. 

Reeves, F. B , Wagner, D. Moorman, T., Kiel, J. 1979. The role of endomycorrhizae in revegetation 
practices in semi arid west. I. A comparison of incideence of mycorrhizae in severely 
disturbed vs. natural environments. Amer J. Bot. 66 : 6-13. 

Safir, G. R., Boyer, J. S., Gerdemann, J. W. 1972. Nutrient status and mycorrhizal enhancement 
of water transport in soybeans. Plant Physiol. 49 : 700-703. 



[ 39 ] 



Spore dispersal of endogonaceae by worms, wasps, dung rollers and 
Indian domestic fowls 

H. C. LAKSHMAN AND S. RAGHAVENDRA 
Karnatak University, Dharwad-580003, Karnataka 

Endogone, the most common fungus component of vesicular arbuscular 
mycorrhizae is non specialized in host range. In association with the host Endogone 
produces in internal mycelium in the cortex and a loose external mycelium bearing 
chlamydospores and zygospores in the rhizosphere and soil. These spores are the 
means of surviral of Endogone the absence of living hosts. Chlamydospores suggest 
that they may be able to survive passage through the digestive system of rodents, 
worms and other animals inhabitans of soil (Dowding, 1959). A number of other 
vectors of VAM fungal spores have been described as early as 1922. Endogonaceae 
spores were observed in the digestive tracts of mullipedes (Thaxter, 1922). 

Present studies reported here deal with the occurrence and dispersal of species 
of Engogonoceae by worms, wasps, dung rollers and Indian domestic fowls. 

Samples of earthworm casting, mud nests of wasps, dung rollers and guana of 
fowls samples were individually collected in different days and placed in polythene 
bags. The contamination of the samples with underlying soil was avoided. Soil 
samples from 5-10 cms depth profile were taken with the help of a 2 cm diameter 
soil sampling tube in the areas immediately adjacent to the worm cast mouls, mud 
nests, dung rollers, and near guana of fowls in the fields. Spores were extracted with 
care using procedure of Gerdemann and Nicolson (1963). The sample of earthworms, 
dung roller and wasps were sacrified by immersion in hot water and then they were 
dissected and intestinal contents were examined for presence of spores. Fowls were 
killed and dissected. Their undigested storage organs were examined for the presence 
of Endogonaceae spores. 

Ten grams of crushed air dried sample material was mixed with 300 g. of red 
loam and placed in plastic containers. The loam soil had been treated previously 
with aerated steam at 65°C for 30 min. to kill any Engogonaceae spores present in 
the soil. The sample materials including worm casts, mud nests, balls of dung and 
fowls samples consisted of steamed soil without additional material. Sunflower seeds 
were planted in the prepared soil and thinned to three plants per container after 
emergence. The plants were grown in garden for 4 weeks. The root systems were 
then carefully washed free of soil and 25 root bits of each 1 cm long were boiled in 

I 40 ] 



10% NaoH and cleaned (Phillips and Hayman 1970). The root bits were stained 
with trypanblue in lactophenol and mounted on microscope slides and the percentage 
of root infection by vesicular arbuscular (VA) Mycorrhizae was determined acording 
to the method of Hayman (1970). 

Spores were found in all samples examined. In general more were extracted 
from the worms casts and mud nests and relatively a few sporse were recovered from 
dung balls. 

VA Mycorrhiza did not develop in the roots of sunflower plants grown in 
steam treated check soil. However, in soils amended with air dried worm cast, mud 
pots, sun flower roots contain 2.4% VAM infection on root infection basis. Dung 
balls and fowls guana soil treatment developed 3% and 3.5% root infection 
respectively. 

The large amount of soil which is constantly being mixed through earth worm 
activity is probably important means of distribution of Endogonaceae spores within 
the soil. The importance of fowls in India, mud nests dung balls in dispersal of the 
fungus is probably rather limited, however, the distance and speed aspects of these ' 
agents should not be over-looked. It appears to us that earth worms bring Endo- 
ganacae spores to the surface. These organisms movements may result in some 
horizontal dispersion. 

REFERENCES 

Dowding. E. S. 1959. Ecology of Endogone. Mycologia 42 : 449-457. 

Gerdemann, J. W., Nicolson, T. H. 1963. Spores of Mycorrhizal Endogone species extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-244. 
Hayman, D. S. 1970. Endogone spore number in soil and vesicular arbuscular mycorrhiza in wheat 

as influenced by season and soil treatment. Trans. Brit. Myco. Soc. 54 : 53-63. 
Phillips, J. M., Hayman, D. S. 1970. Improved proceddure for clearing roots and staining parasitic 

and vesicular arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Brit. , 

Mycol. Soc. 55: 158-161. 
Thaxter, R. 1922. A revision of Endogonaceae. Proc. Am. Acd. Arts. Sci. 57 : 291-922. 



C 4 * 3; 



Survey of Indian arid zone tree species for the occurrence of 
.VAM infections 

J. C. TARAFDAR AND A. V. RAO 
Central Arid Zone Research Institute, Jodhpur-342 003, India 

Vesicular arbuscular mycorrhizal associations with plants are widely distributed 
and are geographically ubiquitous. But there is not much information available on 
the occurrence of mycorrhizae in desert plant species. VAM fungi, a group of 
important soil microorganisms, are known to improve the plant growth through better 
uptake of nutrients and water, resistance to drought and increased tolerance or 
resistance to root pathogens. Water stress and nutrient deficiencies are the common 
constrains that the desert ecosystem experiences. The role of mycorrhizae in the 
building and improving the soil properties is well recognized (Koske et ah, 1975). 
The frequency and density of VAM infections vary widely depending on the plant 
species and soil type (Rani and Mukherjee, 1987). However, knowledge on the 
occurrence of mycorrhizae with tree species of Indian Arid Zone is scanty. The 
present investigation reports the extent of occurrence of VAM infections in different 
tree species growing in different localities of Indian arid zone. 

Twelve plant species from nine environmentally harsh sites in Rajasthan were 
surveyed for the presence of VAM infections. The data indicated that varied types 
of tree species growing at different arid regions were found to have VAM infections 
with their roots. VAM infections were present in all the species examined in different 
locations except in the roots of Salvodora oleiodes collected from Chandan where no 
infection was observed. The intensity of infection varied among the different plant 
species collected from the same place as well as within the same plant species 
collected ftom different locations. For example, VAM infection in the roots of 
Parkinsonia aculeata varies from 25+ (Pokran) to 100+ + + (Bikaner); similarly, 
infection in the roots of Prosopis cineraria varies from 35+ (Dubla) to 95+ + + 
(Lathi). In general infection was more under Lathi (78.3%) and Bikaner (78.1%) 
soils, irrespective of plant species, whereas least infection was observed under Nagaur 
soils (35%). Among the plant species, irrespective of locations, the maximum 
infection was observed under Azadirachta indica (85.8%) followed by Parkinsonia 
aculeata (76.7%) and zizyphus marutiana (73.6%). Of-course plant samples of 
Punica granatum collected only from Bikaner gave 100% infection. 

However, percentage of VAM infections do not vary with plant age. Samples 
collected from Lathi as well as Chandan showed that per cent infection in the roots 

[ 4i ] 



of Albizzia lebbek aged from 3 to 12 months varies only 5-10% whereas no differences 
was observed under Zizyphus marutiana. The denisity of infection did not vary with 
plant age but the young roots mostly carried mycelia with a small number of vesicles 
spores and vesicles were found in matured roots. 

An assessment of the mycorrhizal associations in tree species collected from 
different sites of Indian arid zone was made. The per cent as well as density of 
infection varied with the plant species and the locations. Even the plants of same 
family differed in the intensity of mycorrhizal association in a particular soil. Similar 
differences were recorded in plants of same species collected from different soils. The 
infection rate, in general, is independent of plant age. Most of the VAM fungi 
belong to Gigctsporct, Glomus, Acaulospora and Endogone. 

REFERENCES 

Koske, R. E., Sutton J. E., Sheppard, B. R. 1975. Ecology of Endogone in Lake Huron sand dunes. 

Can. J. Bot. 53 : 87-93. 
Bani, Rekha, Mukherjea, K. G. 1987. Iddian Vesicular-Arbuscular mychrrhizal fungi, proc. 

Mycorrhiza Round Table, New Delhi, pp. 166-180. 



t 43 I 



VAM fungi from the rhizospheres of desert cacti 

JOSE METHEW, NEERAJ, AMY SHANKAR, RAVINDRA KAUR AND AJIT VARMA 

School of Life Sciences, 

Jawaharlal Nehru University, New Delhi. 

The endomycorrhizae of vesicular-arbuscular type develop most commonly in 
majority of the cultivated and wild plant species of arid and semi-arid regions (Singh 
and Varma, 1980; Srivastava et ah, 1989) of western India (a part of Indian Thar 
Desert). The native endophytes play an important role in nutrient uptake and 
biomass production in the region (Slarikis, 1974). The variability in the fungal 
isolates towards root colonization, phosphorus uptake and biomass production have 
been well documented (Khan, 1974). However, no serious effort has yet been made 
to screen the endomycorrhizal isolates to know their role in drought regulation and 
the water use. The desert VAM fungi differ in their ecological requirements and 
adaptability. Little is known about the ecology of such isolates. Very few studies 
have been made on the members of family Cactaceae for mycorrhizal presence (Rose, 
1981; Bloss and Walker, 1987) but to author's knowledge, no systematic study has 
been done on cacti roots and VAM association in India. Cacti are important 
because if spineless, they can be used as supplementary fodder during dry season in 
in deserts (Shankarnarayan and Shankar, 1986). Mycorrhizal fungi help in the 
formation of or preservation of soil structure, in the uptake of bound soil water and 
increased internal nutrition of their host plants (Sieverding, 1981). Kirkun et ah, 
(1987), Singh and Varma (1988) and Neeraj et ah, (1989) have studied the mycorrhi- 
zal associations with plants in stressed environments and found it of great biological 
significance. The aim of this study was to screen and select species of VAM fungi to 
determine host-fungus combinations under stressed soil and climatic conditions to 
explore their possible applications in plant- VAM associations. 

Root and rhizosphere soil samples of Opuntia coccinlillifera, O. cylindrica, O. 
ficus indica, O. santarita, O. vulgaris and Opuntia sp. were collected from Jodhpur 
district of Rajasthan in the months of December 1988 and March 1989. Tempera- 
ture of the soil-30 cm below the surface was noted at the time of sample collection. 
The roots of the respective plants were cut into 1.0 cm long segments, preserved in 
FAA and brought to the laboratory. These were cleared and stained with Trypan 
Blue. Presence of mycorrhizal infection in 100 root segments was observed using 
light microscope. 



Soil moisture and pH was determined immediately after bringing the soil 
samples to the laboratory. The soil samples were air dried and stored at 4°C in air 
tight polythene bags. Wet sieving and decanting method (Gerdemann and Nicol- 
son, 1963) followed by sucrose centrifugation (Smith and Skipper, 1979) was used for 
isolating the VAM spores from 50 gm air dried soil. The spores were mounted in 
PVLG for observations and identified with the help of the key of Hall and Fish 
(1979) and the Manual of the Manual of Schenck and Perez (1987). 

Most of the Cactus plants studied were mycorrhizal but there was a 
great deal of variations in their percentage of root infection . O. coccinlillifera had 
maximum infection (35.6%) and Opuntia sp. the minimum (12%). The former had 
high infection density followed by 0. cylindrica. Significantly, no arbuscules were 
seen. The spore number in rhizospheres varied with the season, host species and the 
physical properties of the soil. 

In winters the number of VAM spores in the rhizospheres of Opuntia sp. and 
O. coccinlillifera was 240 (±6) and 328 (±8) respectively, wherease in spring Opuntia 
sp. had 332 spores and 0. vulgaris 1142. Strikingly, Glomus macrocarpum not only 
dominated the spore population but also was common to all the six hosts studied. 
The other common species was Sclerocystis sinuosa associated with O. ficus, 
O. cylindrica and O. vulgaris. Spores of G. fasciculatum, G. feugianum, G. geosporum, 
G. mosseae, G. reticulatum, Gigaspora Candida and Entrophospora infreguens were the 
other type species isolated from the rhizosphere soils. E. infreguens was observed 
only with the O. ficus. Its spores were orange brown, 96 /tm dia., subglobose 
or ellipsoidal, contents oily, globular, vesicle subglobose to ellipsoid 128x153 /tm 
and attached to the spore. Sporocarps of 5". sinuosa were 175-235x 187-257.5 /tm, 
light brown to golden brown and usually tuberculate, enclosing obovate, elliptical, 
fusiform or clavate, 37.5-80x32.5-45 /*m and chlamydospores in a peridium were 
made up of interwoven sinuous hyphae. Chlamydospores were arranged radially 
around a plexus of hyphae. 

Absence of the arbuscules in the root system may indicate the nonfunctional 
mycorrhizal associations or non-symbiotic colonization by hyphae from a mycorrhi- 
zal plant growing close by. Even if the plants are widely spaced^ colonization from 
a neighbouring plant may occur. At Pereseat it can not be stated with certainty 
whether the mycorrhizae of the species are viable or structural remnants from a 
once-functional association (Hirrel et al; 1978). 

The number of spores produced in the spring was higher than in the winter. 
This observation is in agreement with Steffeldt and Vogt (1975). Rose (1981) 
reported the presence of mycorrhiza in Cardo cactus (Pachycereus pringlei) and 
Opuntia sp. roots but no spores were encountered in the rhizosperes whereas 
Machaerocereus gummosus had VA fungi neither in the roots nor in rhizosphere soils. 
In such cases the questions raised by Hirrel et al. (1978) may have weightage. We 

[45 ] 



have found both the VAM hyphal system in the roots as well as the VA spores in 
rhizosphere soils irrespective of the host species and their geographical distribution. 
This strongly suggests that the Cacti studied were truely mycorrhizal and spores 
heavily colonized the plant root system. 

Low moisture content (3.5% in winter and 2.0% in spring) and pH value 
ranging from 8.3 to 8.96 indicate that these fungi can induce severe water stress 
conditions and survive well in alkaline soil conditions. The average temperature 
recorded at mid-day was 30°C which is usually favourable for fungal growth. 

REFERENCES 

Bloss, H. E , Walker, C. 1987. Mycologia 79 : 649-654. 

Gerdemann, J. W., Nicolson, T. H. 1963. Trans. Brit. Mycol. Soc. 46 : 335-244. 

Hall, I. R., Fish, B. J. 1979. Trans. Brit. Mycol. Soc. 73 : 261-270. 

Hirrel, M. C, Mehravaran, H., Gerdemann, J. W. 1978. Can. J. Bot. 56 : 2813-2817. 

Khan, A. G. 1974. /. Gen. Microbiol. 81 : 7-14. 

Krikun, J., Hass, J. H., Bar Yousef 1987. Angew Botanik 61 : 97-105. 

Neeraj, Shankar, A., Mathew, J., Varma, A. K. 1989. Fifth Inter. Symp. Microb. Ecol, Kyoto, 
Aug. 27-Sept. 1. pp. 136. 

Rose, S. L. 1981. Can. J. Bot. 59 : 1056-1060. 

Schenck, N. C, Perez, Y. 1987. Manual for the Identification of VAM Fungi (INVAM). 

Shankarnarayanan, K. A., Shankar, V. 1986. In : Desert Environment Conservation and Manage- 
ment CAZRI, Jodhpur. 

Singh, K., Varma, A. K. 1980. Trans. Brit. Mycol.Soc. 21 : 477-482. 

Singh, K., Varma, A. K. 1981. Trans. Brit. Mycol. Soc. 77 : 655-658. 

Singh, K., Varma, A. K. 1988. Proc. National Workshop on Mycorrhizae, Delhi, 1987. pp. 
356-371. 

Sieverding, E. 1981. /. Ag. Crop Sc. 150 : 400-411. 

Slarikis, V. 1974. Ann. Rev. Phytopath. 12 : 437-457. 

Smith, G. W., Skipper, H. D. 1979. Soil Sc. Soc. Amer. J. 43 : 722-725. 

Srivastava, H. P., Vyas., A., Chandel, S. 1989. Fifth Inter. Symp. Microb. Ecol., Kyoto, Aug. 
27-Sept. 1., pp. 137. 

Staffeldt, E. E., Vogt, K. B. 1975. US/IBP Desert Biome. Rep. 1974. Prog. 3 : 63-69. 



[ 46 ] 



Occurrence of VA-mycorrhizal associations with fruit and ornamental 
plants 

K. P. RAVERKAR, K. MEHTA* AND A. R. BHANDARI 

Department of Soil Science and Water Management Dr. Y. S. Parmar University of 

Horticulture and Forestry, Nauni-Solan (H.P.)-173230 

The importance of VA-mycorrhizal associations to agricultural and forest 
plants have been well documented. However, meagre information is available about 
the occurrence of VA-mycorrhizal associations with fruit plants in general and 
temperate fruits in particular. Similarly, VAM fungal associations in ornamental 
plants too, have received very little attention. Mycorrhizae are important in maxi- 
mizing ornamental and fruit plant's productivity. The understanding of mycorrhizal 
associations is necessary for wise management of tnese plants. A preliminary report 
on the distribution of VA-mycorrhizae in some fields of the country highlights the 
necessity and importance of such survey (Phillips and Hayman, 1970). 

Keeping in view, the information regarding the distribution and occurrence of 
VA-mycorrhizal associations with ornamental and temperate fruit plants grown in 
Himachal Pradesh-the horticulture state of the country, it will be of immense help to 
the state, to improve its production and quality of fruits and flowers. A part of our 
investigations is reported in the present communication, which includes the occurrence 
of VAM fungal associations in some temperate fruit and ornamental plants. 

During June, 1989 roots of temperate fruits (Apple, Peach, Wild apricot and 
Kainth) and ornamental plants (Chrysanthemum, Sylvia, Zinnia, Balsam and 
Marigold) were collected from different nurseries of the university. Roots were 
collected from five plants of each species. Samples of thin lateral roots were excised 
from the main laterals of each plant and stored in sealed container until analysis. 

To assess mycorrhizal fungal colonization, 50 fine root segments, measuring 
1 cm in length excised from the lateral root specimens were washed, cleaned and 
differentially stained following the procedure of Philips and Hayman (1970) with some 
modifications. The per cent mycorrhizal colonization was determined by using the 
systematic slide method (Hayman, 1970). 

Four fruit and 5 ornamental (flowering) plants were surveyed and observed 
for VA-mycorrhizal associations from Solan. AH the fruit as well as ornamental 

♦Department of Fruit Culture and Orchard Management 
[ 47 ] 



plant's species were VA-mycorrhizal, with vesicles or arbuscules and intracellular 
hyphae in the root cortical cells. The per cent colonization varied with the plant 
species. The VA-mycorrhizal colonization in the fruit plants ranged from 8.51-18.05%, 
highest being in Primus armeniaca and lowest in Pyrus pashia. Vesicle formation 
was noticed in all the four fruit plants the number of which ranged from 0.09 to 
2.24 cm -1 of root tissue. The highest number of vesicles were registered in Prunus 
armeniaca. The mycorrhizal colonization in ornamental plants ranged from 5.72 to 
16.46%. Highest mycorrhizal colonization was recorded in Chrysanthemum marifalium 
whereas lowest in the Zinnia elegans. No arbuscules and vesicles formation was 
noticed in Zinnia elegans and Impatiens balsamina. 

The per cent mycorrhizal colonization was related to the number of vesicles 
formed in root tissues. Vesicles being a reproductive structure, in addition to carbo- 
hydrate containing organ, it could have helped in multiplication of VA-mycorrhizal 
and subsequently in increased colonization. As the, natural mycorrhizal colonization 
- in both fruit as well as ornamental plants was found to be poor, there is a immense 
need to exploit the mycorrhizal, associations with these plants by using artificial 
inoculum, which may prove significantly beneficial in better management of these 
crops. 

REFERENCES 

Hayman, D. S. 1970. Endogone spore numbers in soil and vesicular-arbuscular mycorrhiza in 
wheat as influenced by season and soil treatment. Trans. Brit. Mycol. Soc. 54 : 5 . 

Phillips, J. M., Hayman, D. S 1970. Improved procedures for clearing roots and staining 
parasitic and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. 
Trans. Brit. Mycol. Soc. 55 : 158-160. 



Growth and nutrient uptake of Eucalyptus camaldulensis and 

Pinus caribaea var. hondurensis seedlings grown on old 

tin-mined soils after Pisolithus tinctorius ectomycorrhizal 

inoculation and manure fertilization 

ANIWAT CHALERMPONGSE AND SOMBOON BOONYUEN 

Forest Pathology and Microbiology 

Royal Forest Department, Bangkok-10900, Thailand 

After 6 months of trial by using Pisolithus tinctorius (Pers.) Coker and Couch 
ectomycorrhizal inoculation and manure fertilization with Eucalyptus camaldulensis 
Dehn. and Pinus caribaea More. var. hondurensis Barr. and Golf, seedlings grown on 
tin-mined soils contained in polythene bags in nursery at Central Forest Research 
Laboratory and Training Center, Royal Forest Department, Bangkok, Thailand 
during February to September, 1986 was experimented by a split-split plot in 
completely randomized design comprising uninoculated ectomycorrhizal and non- 
manure fertilized treatments as control. 

Results showed that plant height, growth (diameter at root collar) and total 
biomass (stem, foliage and root) of test seedlings were significantly increased than 
uninoculated ectomycorrhizal and non-manure fertilized treatments. Growth perform- 
ance of E. camaldulensis was closely prominent in correlation with manure fertilization, 
followed by ectomycorrhizal inoculation and manure fertilization plus ectomycorrhizal 
inoculation, respectively. The growth response of P. caribaea var. hondurensis was 
also obviously correlated with manure fertilization plus ectomycorrhizal inoculation 
and merely ectomycorrhizal inoculation, respectively. Nutrient uptake in shoot 
(foliage plus stem) of E. camaldulensis seedlings was exhibited at a larger amount 
than those of control treatment by Mg(40.8%), Ca(32.1%), P (9.7%), N(3.5%) 
and K (1.8%), respectively; whereas P. caribaea var. hondurensis was indicated by 
Ca(35.7%), Mg(26.5%), K(21.4%), P(13.3%) and N(1.3%), respectively. 
Distinctinctively more consumption *>f nutrients in P. caribaea var. hondurensis 
seedlings after 6 months of experiment seemed to be ascertained than those of E. 
camaldulensis seedlings. 

[ 49 ] 



This finding suggests that ectomycorrhizal inoculation and manure fertiliza- 
tion promote vigour, durability and survival of prepared seedlings before transplan- 
ting to reforest in the old tin-mined areas. Remarkedly, manure fertilization in 
cooperation with P. tinctorius ectomycorrhizal inoculation to seedlings should be 
applied with care, because manure actually affected the increase of soil pH and 
stunted the growth of P. tinctorius ectomycorrhizal fungus. It is also evident that P. 
tinctorius revealed more symbiotic association with P. caribaea var. hondurensis than 
E. camaldulensis. 



I 50 ] 



Photoassimilate partitioning and translocation in mycorrhizal 
sorghum 

MOHAN SINGH AND K. V. B. R, TILAK 
Division of Microbiology, Indian Agricultural Research Institute, New Delhi-1 10012 

Vesicular-arbuscular mycorrhizal (VAM) fungi derive carbon compounds from 
their host plants and use them as source of energy. This affects host carbon meta- 
bolism. Increased rate of CO a assimilation and higher amount of carbon translocation 
from shoot to root of mycorrhizal plants are some of the reported adaptations by 
which plants respond to the increased demand for carbon by the mycosymbiont 
(Harold, 1980). Increase in rate of C0 2 assimilation in mycorrhizal plants has 
mainly been ascribed to increased assimilatory area associated with lowering of dry 
matter in leaves, rather than to higher rates of photosynthesis (Pang and Paul, 1980). 
Such a differential partitioning of assimilated carbon to plant parts is, however 
controversial (Harris et at, 1985). In the present study translocation and partitioning 
of assimilated carbon was followed using radioactive carbon dioxide in mycorrhizal 
and non-mycorrizal sorghum plants. 

Mycorrhizal and non mycorrhizal plants of sorghum were grown in pots for 
six weeks. Non-mycorrhizal plants received phosphorus to achieve P nutrient status 
similar to that of mycorrhizal plants. The shoot dry weight, root : shoot ratio and 
shoot phosphorus concentration were similar, while leaf area, specific leaf area and 
leaf area ratio were 33, 39 and 40 per cent higher in mycorrhizal than non- 
mycorrhizal plants, respectively. These plants were used for labelling with 14 CO a . 
Ths 14 C assimilates were transported from labelled leaf to other leaves, stem and roots 
of both mycorrhizal and non-mycorrhizal plants within 24 hr of chase period. In 
labelled leaf, only 37 and 43 per cent of the total activity was retained in mycorrhizal 
and non-mycorrhizal plants. There were no differences in the amounts of activity 
present in stem and leaves of both types of plants. However, roots infected with 
Glomus versiforme contained 20 per cent as compared with that of 14 per cent present 
in the roots of non-mycorrhizal sorghum plants. 

The ethanol soluble fraction contained 62 and 46 per cent of the total activity 
present in the leaves of mycorrhizal and non mycorrhizal plants. Acid digested 
fraction of labelled leaf from mycorrhizal plants showed 34 per cent compared with 
that of 49 per cent of activity in non-mycorrhizal plants. In the lipid fraction, there 
was no much variation between mycorrhizal and non-mycorrhizal plants. 

[ 51 ]" 



In the roots, the amount of activity present in ethanol soluble fraction was 51 
per cent and 62 per cent in mycorrhizal and non mycorrhizal plants. Acid digested 
fraction contained 46 and 36 per cent of the total activity present in mycorrhizal and 
non-mycorrhizal plants. 

The distribution of 14 C-assimilated carbon to plant parts indicates that about 
6 per cent more of the total carbon was translocated from shoot to root of mycorrhi- 
zal than non-mycorrhizal plants within 24 hr. of the chase period. This additional 
amount of carbon was supplied by the labelled leaf of mycorrhizal plants without 
affecting the amount of assimilates being distributed to other tissues. This observation 
substantiate that higher amounts of photosynthates are translocated from shoot to 
root of mycorrhizal j than non-mycorrhizal plants without decreasing the leaf area 
(Pang and Paul, 1980). The specific leaf area, therefore showed an increase of 
40 per cent. 

Development of a carbon sink in the plant normally influence upon partitioning 
and distribution of assimilated carbon. Our results also indicates that establishment 
of VAM in sorghum altered the distribution of C assimilates into ethanol soluble and 
acid digested fraction of leaves and roots. Higher amount of the activity recovered 
from the ethanol fraction of the labelled leaf suggested that carbon in greater amount 
is being transfered from shoot to root of mycorrhizal plants. 

The variations observed in partitioning of assimilated carbon into different 
chemical fractions of roots may be attributed to the altered metabolic activities of 
mycorrhizal than non-mycorrhizal plants (Kucey and Paul, 1982). 

REFERENCES 

Harold, A. 1980. Regulation of photosynthesis by sink activity : the missing link. New Phytol. 

86 : 131-144. 
Harris, D., Pacovsky, R. S., Paul, E. A. 1985. Carbon economy of Soybean-Rhizobium-Glomus 

associations. New PhytoL 101 : 427-440. 
Kucey, R. M. N., Paul, E. A. 1982. Carbon flow, photosynthesis and N a fixation in mycorrhizal 

and nodulated faba beans. Soil Bio. Biochem. 14 : 407-412. 
Pang, P. C, Paul, E. A. 1980. Effects of vesicular-arbuscular mycorrhiza on C and N distribution 

in nodulated faba beans. Can. J. Soil Sci. 60 : 241-250. 



I 52 ] 



Sporulation in Glomus mosseae under in vitro conditions 

ALOK ADHOLEYA AND SUNIL KHANNA 

Microbiology and Molecular Genetics Section, 

Tata Energy Research Institute, 

7, Jor Bagh, New Delhi - 110 003 

Fungi which form vesicular arbuscular mycorrhizae (VAM) have not been 
cultivated in vitro and so it is difficult to produce large quantity of fungal biomass 
for biochemical and genetical analysis. The collection of extramatrical mycelium/ 
vesicles/spores is time consuming and cause physical damage to the fungus. These 
difficulties have restricted the progress of fundamental research with these fungi. 

There have been numerous studies on the axenic growth of VAM fungi 
in medium. Hepper (1983) showed the development of hyphae from germinating 
resting spores of Glomus caledonius which were viable even after detachment from 
their parent spore. Louis and Lim (1988) showed the formation of extramatrical 
vesicles in Glomus clarum. Recently Burggraff and Beringer (1989) showed the 
formation of secondary spores in in vitro culturing of Glomus caledonius which when 
subcultured yielded immatured spores. 

One of the essentials of axenic propagation of VAM endophyte is good spore 
germination followed by proliferation of mycelium and sporulation. The present 
investigation has examined the requirements for axenic spore germination in Glomus 



Spores of Glomus mosseae (Nicol and Gerd.) Gerd. and Trappe were isolated 
by wet sieving and decanting method (Gerdemann and Nicolson, 1963). The spores 
were then purified from root pieces and debris by sucrose gradient centrifugation by 
the method of Jenkins (1984) modified as follows : The spore suspension was layered 
onto a 5M sucrose solution and centrifuged at 400 'g' for 3 minutes at 4°C in a 
swing bucket rotor. The concentrated spores (with less amount of debris) formed a 
layer in the upper half of the gradient. These spores were subjected to sucrose 
density gradient centrifugation four times for getting purified spores free from debris. 
The concentrated spores were then washed repeatedly with water to remove sucrose. 
These purified spores were surface sterilized with sodium hypochlorite (2.5% V/V) 
for 30 minutes and washed repeatedly with sterile distilled water to remove traces of 
sodium hypochlorite. These spores were then used for germination studies. 

Germination of G. mosseae observed with different combinations of agar, 
sucrose and soil extract showed very marginal differences. The addition of root 

[ 53 ] 



extract either from maize or mung bean, soil extract or sucrose (2%W/V) respectively 
did not enhance hyphal proliferation and spore formation as compared to agar 
(0.8% Himedia W/V) alone. Thus in all further experiments agar medium was 
used. 

The effect of light, moisture and aeration was studied on spore germination. 
The spores incubated in dark, germinated and showed hyphal elongation while in the 
presence of light they failed to do so. To study the effect of moisture and aeration, 
the Petri dishes were wrapped with nescofilm just after inoculation. In another set 
nescofilm was not wrapped. It was observed that the application of nescofilm 
resulted in extended hyphal proliferation (up to three weeks) whereas the proliferation 
ofhyphaein Petri plates without nescofilm stopped after two weeks. During this 
experiment it was also observed that freshly prepared Petri plates showed improved 
spore germination and proliferation of hyphal as compared to plates which were 
more than three day old at room temperature. Thus in all further experiments- 
freshly prepared Petri dishes were incubated after inoculation in dark and wrapped 
with nescofilm. 

The spores when incubated on the simple water agar medium formed germ 
tube after 48 hrs. These hyphae emerged either from the hyphal attachment point 
or directly through the spore wall. Proliferation af these hyphae was observed and 
after 6 days of incubation small globular structures were visualized. These were 
single walled hyaline in appearance and after another 10-12 days double walled dark 
globular structures were observed. Hyphal proliferation was observed only up to 
three weeks after spore germination. These secondary spores did not germinate 
even after 6 weeks of incubation. The secondary spores so obtained were transferred 
to fresh medium but no germination was observed. This clearly indicated that 
environmental conditions were not a limiting factor for spore germination. 

The secondary spores were tested for their viability and infectivity. Positive 
infectivity was observed for these spores thus indicating their infective capability. 

REFERENCES 

Burggraff, A. J. P., Beringer, J. E. 1989. Absence of nuclear DNA synthesis in vesicular-arbuscular 

mycorrhizal fungi during in vitro development. New Phytol. Ill : 25-33. 
Gerdemann, J. W., Nicolson, T. H. 1963. Spores of a mycorrhizal Endogone species extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-244. 
Jenkins, W. R. 1964. A rapid centrifugal-flotation technique for separating nematodes from soil. 

Plant Dis. Rep. 48 : 692. 
Hepper, C. M. 1983. Limited independent growth of a vesicular-arbuscular mycorrhizal fungus 

in vitro. New Phytol. 93 : 537-542. 
Louis, I., Lim, G. 1988. Effect of storage of inoculum on spore germination of a tropical isolate 

of Glomus clarum. Mycologia 80 : 157-161. 



[ 54 ] 



Enhanced phosphatase activity in mycorrhizal papaya (Carica 
papaya cv. Coorg Honey Dew) roots 

SUKHADA MOHANDAS 
Indian Institute of Horticultural Research, Hessaraghatta, Bangalore-560 089 

The presence of active phosphatases on the surface of beech mycorrhizas 
catalyzing hydrolysis of complex phosphates have beeu demonstrated by Bartlett and 
Lewis (1973). Capaccio and Callow (1982) studied the specific phosphatases of 
mycorrhizal onion roots responsible for the synthesis and degradation of polyphos- 
phates. Krishna et al. (1983) further demonstrated the correlation between phosphate 
uptake and non-specific phosphatase activity in roots of mycorrhizal Arackis hypogea 
L. Studies conducted in our laboratory revealed that papaya (Carica papaya cv . 
Coorg Honey Dew) responded excellently to VAM inoculation and phosphorus 
content in the leaves increased by 30-35% in inoculated plants compared to controls 
(Sukhada, 1988). Hence, it was thought worthwhile to study the activity of acid and 
alkaline phosphatases in papaya roots which might have been the potential agents 
causing phosphate increase in leaves. 

Experiments were conducted with 3 month old papaya plants grown in pots 
(containing sand : soil mixture 1 : 1, pH 6.0, available P 63 ppm (Olson) and 
inoculated with cultures of Glomus mosseae and G.fasciculatum. 

Root surface activity was tested by incubating five 1 mm unbranched root tips 
in P-nitrophenol phosphate (1.5 ml of 1 mg/ml solution) and 0.5 ml. 0.25 M sodium 
acetate buffer pH 6.0 (for acid phosphatase) or Tris-Hel buffer (for alkaline phos- 
phatase) and thereafter stopping the reaction with 5 ml of 0.1 N NaOH and recording 
absorbance at 410 nm. Similarly 0.2 ml enzyme extract (obtained by macerating 
the root tissue in 0. 1 M phosphate buffer) and 1 g of root surrounding the root region 
of the plants were tested for acid and alkaline phosphatase activity which was expres- 
sed as n moles of P-nitrophenol released per gram fresh weight of tissue or soil per 
hour. 

Results revealed that there was an enhanced activity of acid and alkaline phos- 
phatase (ranging from 25 to 114%) on the root surface in the enzyme extract from 
the root and soil surrounding the root region of mycorrhizal plants over uninoculated 
plants. Acid phosphatase activity was considerably more than alkaline phosphatase. 
G. mosseae inoculated plants showed better activity than G. fasciculatum inoculated 
plants. 

[ 55 ] 



As there was a relation between the mycorrhizal infection, phosphorus content 
in the leaves and dry matter accumulation in the plant it is concluded that mycorrhi- 
zal infection helped in efficient utilization of phosphate by enhancing phosphatase 
activity in the roots which breaks down complex phosphates and increases availability 
of phosphates to the plant. Further work on specific phosphatases involved in the 
process is interesting to pursue. 

REFERENCES 

Bartlett, E. M., Lewis, H. D. 1973. Surface phosphatase activity of mycorrhizal roots of beech. 

Soil Biol- Biochem. 5 : 249-251. 
Gapaccio, L. C. M, Callow, J. A. 1982. The enzymes of polyphosphate metabolism in vescicular- 

arbuscular mycorrhizas. New Phytol. 91 : 81-91. 
Krishna, K. R., Bagyaraj, D. J.. Papavinasasundaram, K. G. 1933. Acid and alkaline phosphatase 

activities in mycoirhizal uninfected roots of Arachis hypogea L. Arm Bot. 51 : 551-553. 
Sukhada, M. 1988. Response of papaya (Carica papaya cv. Coorg Honey Dew) to inoculation 

with mycorrhizal fungi. In: Mycorrhizae for Green Asia, Eds. A Mahadevan, N. 

Raman, K. Natarajan, CAS in Botany Uni. of Madras-600025, pp. 260-261. 



C 56 ] 



Characterization of mycorrhiza-specific alkaline phosphatase from 
french bean 

KAMANA KUMARI, D. P. MISHRA AND B. N. JOHRI 

Departments of Biochemistry and Microbiology, G. B. Pant University of 

Agriculture and Technology, Pantnagar (Nainital) U. P. 

French bean {Phaseolus vulgaris L.) is one of the most important legume crops. 
In tarai region of Uttar Pradesh (India) it forms poor nodulation and requires very 
high nitrogen fertilization (Smith and Daft, 1977). Phosphorus is by far the most 
important nutrient, because it not only affects growth response of plants, but also 
influences VAM infection and development (Gianinazzi and Gianinazzi, 1978). 
Improved P nutrition in VAM associated plants results from an increased efficiency 
of P uptake from the soil (Sanders and Tinker, 1973). 

The increased transfer of P from soil to the mycorrhizal plant appears to be 
due to a result of absorption, transport and release of available P by the symbiont to 
the host root rather that a specific stimulation if ion uptake by infected or uninfected 
host cells (Hayman, 1983). Relatively little is known concerning the mechanisms and 
Pathway of P metabolism within the external hyphae of the endophyte although its 
release in the host is an active process (Hayman, 1983). 

Alkaline phosphatase (pH optimum 9-10) acts on phosphoric esters, with the 
liberation of inorganic phosphate. The available literature on the activity of alkaline 
phosphatase suggests that the enzyme is localized in the vacuoles of the mycorrhizal 
fungus. It appears with the proliferation of the hyphae, but becomes particularly 
intense in mature arbuscules and intercellular hyphae, polyphosphate like granules 
have been indentified within these vacuoles in Glomus caledonicus which are thought 
to be involved in phosphate transport mechanism (Hayman, 1983). The vacuole is 
regarded as an active system which plays an important role in the transport 
mechanism. 

But little efforts have been made to examine the make up of alkaline phospha- 
tase as influenced in plants inoculated with mycorrhizal spores. 

Alkaline phosphatase was purified from NM and M treated plants on 45th 
day. The enzyme preparation from NM and mycorrhizal french beans was purified 
using sephadex gel chromatography and DEAE 52 to achieve 71,103 and 73,121 fold 
purification. 

[ 57 ] 



The purified preparations gave a single band on 5 to 10% gradient PACE. A 
single protein peak was observed by UV spectrophotometry with an absorption 
maxima at 275 nm. The Vmax and Km differed slightly for the two preparations but 
they had similar pH (8.5) and temperature (40 C C) optima. The molecular weight of 
the alkaline phosphatase from non-mycorrhizal french beans was found to be 139,000 
daltons. Whereas subunit molecular was 67,000. This enzyme preparation showed 
a wide substrate specificity as compared to the alkaline phoshatase purified from 
plants infected with VA mycorrhiza. Both the enzyme preparations showed end 
product inhibition towards pi and mycorrhizal association showed modification of 
alkaline phosphase. 

Mycorrhizae are known to enhance the phosphate uptake by enhancing 
phosphatases activity. Phosphatases play an important role in the solubilization of 
phosphorus from non-available phosphorus sources. Alkaline phosphatase play an 
important role in catalyzing the hydrolysis of complex phosphate esters. Alkaline 
phosphatase is known to help in the solubilization of phosphorus sources and thus it 
can provide additional phosphorus for important metabolic processes which lead to 
improved production and yield. 

REFERENCES 

Gianinazzi, P., Gianinazzi, S. 1978. Enzymatic studies on the metabolism of vesicular arbuscular 
mycorrhiza. I : Effect of mycorrhiza formation and phosphorus nutrition on soluble 
e activities in onion roots. Physiol Veg. |4 : 833-841. 



Hayman, D. S. 1983. The physiology of vesicular arbuscular endonycorrhizae symbiosis. Can. 

J. Bot. 61 : 944-963. 
Sanders, F. E., Tinker, P. B. 1973. Phosphate flow in to mycorrhizal roots. Pest. Sci. 

4 : 385-395. 
Simith, S. E., Daft, M. J. 1977. Interaction between growth, phosphate content and nitrogen 

fixation in mycorrhizal and non-mycorrhizal Medkago sativa. Aust. J. Plant Physiol. 

4 ; 403-413. 



[ 58 ] 



Nitrate reductase activity of vesicular-arbuscular mycorrhizal fungi 

K. V. B. R. TILAK AND DWIVEDI 

Division of Microbiology 
Indian Agricultural Research Institute 

New Delhi-110012, INDIA 

Capability of reducing or utilizing the nitrate ions by several ectomycorrhizal 
fungi has already been reported by various workers (Plassard et ah, 1987). Endo- 
mycorrhizal fungal species like Glomus macrocarpus and G. mosseae have also been 
known to reduce nitrate ions (Ho and Trappe, 1975). However, so far. there is no 
systematic report available on nitrate reducing ability of different meinbers of 
endomycorrhiza. The present paper embodies the results on the= nitrate reducing, 
capacity of the spores of different vesicular-arbuscular mycorrhizal fungi. 

Extramatrical chlamydospores of Glomus fasciculatum, G. mosseae, G. intrara- 
dices, G. caledonicum, Gigaspora margareta, G. calospora, Endogone duscii and 
Acaulospora sp. were collected from single species pot cultures maintained with 
Cenchrus cilliaris using wet sieving and decanting technique (Gerdemann and 
Nicolson, 1963). Ten samples of 200 sporeS each were surface sterilized with 1.0% 
chloramine T for 20 minutes and washed three times with sterile distilled water to get 
rid of the traces of sterilizing agent. Each sample was put in a Thunberg tube to 
which was added 3 ml of phosphate buffer (pH-7.0), 1.0 ml of 0.1 M succinic acid 
and a drop of 0.003% streptomycin in order to arrest the bacterial growth. ^Five 
samples received 1 mi of 0.1 M KN0 3 each. The other five samples served as control' 
which received 1.0ml sterilized distilled water instead of KN0 3 . The samples were 
checked for bacterial contamination by plating themfon nutrient agar medium and 
incubated at 30 D C. No growth was noticed even after 3 days of incubation. The 
tubes were sealed under oxygen free conditions and incubated at 30°C for 24 hr. 
Nitrate reductase activity was assessed and was expressed as /* moles nitrate formed 
per sample. 

The results revealed that all the vesicular-arbuscular mycorrhizal fungal spores, 
exhibited the property of nitrate reducing ability and it varied from 1.5 n moles to 
3.8 n moles/tube 24 hr. The maximum nitrate reductase activity was noticed with 
Glomus caledonicum and the lowest activity was recorded with Acaulospora sp. The 
other endomycorrhizal fungi recorded intermediate values. No activity was detected 
in any control treatment, indicating thereby that there was no contribution of nitrite 

[ 59, ] 



to the solutions from the spores or extraneous sources. Occurrence of nitrogen 
fixing Azospirilla from the surface sterilized spore of VA-mycorrhizal has been 
reported (Tilak et al., 1987). It is likely that these diazotrophs present inside the 
chlamydospores might have resulted in nitrate reduction. 

The results in the present investigation suggest that with a capacity for 
reducing nitrate it is likely that the symbiotic effectiveness of the vesicular-arbuscular 
mycorrhizal fungi is enhanced in terms of nitrogen assimilation and translocation to 
the host plant. However, further physiological and biochemical studies on the 
interaction of host and endomycorrhizae should lead to a better understanding of the 
mechanism of nitrate reduction by vesicular-arbuscular mycorrhizal spores. 

REFERENCES 

Plassard, C, Scheroms, P., Porcher, P., Mousain, D , Bousquet, N., Tillard. P., Labarire, J., 

Salsec, L. 1987. Nitrate reductase and phosphatase activities in ectomycorrhizal isolates. 

FKW. 7*b Niprth Amer. Conf. Mycorrhizae, Gainesville, Florida, USA, pp. 258. 
Ho, I., Trappe, J. M. 1975. Nitrate reducing capacity of two vesicular arbuscular mycorrhizal 

fungi. Mycologia 4 : 886-888, 
Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-244. 
Tilak, K. V.B. R., Li, C. Y., Ho, I. 1987. Recovery of nitrogen fixing AzoipiHllum from spores 

of VA-mycorrhizal fungi. Proc. 7th North Amer. Conf. Mycorrhizal, Gainesville, 

Florida, USA, pp. 223. 



[ 60 ] 



The response of mycorrhizal maize plants to variations in water 
potentials 

B. RAMAKRISHNAN, B. N. JOHRI AND R. K. GUPTA 

Departments of Microbiology and Environmental Science, G. B. Pant University, 

Pantnagar-263 145, India 

Plant and water stress is considered a major limiting factor in crop producti- 
vity. Water stress can have profound metabolic influence on plant resulting not 
only in impaired gas exchange but also in considerable alteration of physiological 
processes (Hsiao, 1973). Vesicular Arbuscular mycorrhizal association in plants 
contributes towards the development of resistance to water stress. It may be attribu- 
ted to imoroved phosphate nutrition or reduced stomatal resistance or its influence 
on the root/shoot hormonal balance (Nelson and Safir, 1982). However, the 
mechanism of resistance is not clear. Present study, therefore, was carried out to 
find out the response of maize inoculated with VAM fungus Glomus caledonius under 
various osmotic stresses. 

Five surface sterilized Seeds of maize (Zea mays L. var. HS 123) were planted 
per pot filled with 2 kg of sand : Phosphorus deficient soil (3.5 ppm available P) 1 : 1 
mixture. Potting mixture was autoclaved on three alternate days. Thinning was 
done to maintain three seedlings per pot. Parallel experiments were carried out with 
unsterile soil. An inoculum containing approximately 400 spores of G. caledonius 
(Nicol. and Gerd.) Gerdemann and Trappe, obtained from the Rothamsted Experi- 
mental Station, UK was used per pot. Plants were grown in a glass house with day 
temperature ranging 24 to 32 °C and were watered daily. Under sterile soil, five 
week old VAM plants exhibited 48% infection while under non-sterile soil it was 
about 38%. 

Five week old non-VAM and VAM plants were exposed to osmotic potentials 
of 0, -2, -5 and -10 bar (Goyal and Gupta, 1985). After 8 hours of exposure, leaf 
water potential using Pressure Chamber Instrument (PSM Instrument Company, 
Oregon, USA) was measured. They were about -3, -5, -8 and -12 bar under varying 
osmotic potentials in the case of both non-VAM and VAM plants. Net photosyn- 
thesis ("C0 2 dpm/cm a ) was found to increase insignificantly at 0, -2 and -5 osmotic 
potentials. But at very low osmotic potential (-10 bar), there was a significant 
increase in the assimilation of 14 C0 8 by the VAM plants (10.36%). On lowering the 
the water potentials, the rate of decrease in the assimilation of C0 2 in VAM plants 

[ 61 ] 



was very little as compared to the rate of non-VAM plants. Among the VAM plants 
and non-VAM plants, the difference in total chlorophyll content was nonsignificant 
at all low osmotic potentials. 

The ability and efficiency of VAM plants to- survive under drought stress was 
studied. Stomata begin to close earlier if leaf water potential reaches the threshold 
level for closure (Allen and Boosalis, 1983). The result of present study showed that 
there was no change in the leaf water potentials suggesting the mycorrhizal influence 
on stomatal regulation. Net assimilation rate was increased significantly only at low 
water potential. No change had been observed in the levels of total chlorophyll 
content among them. A difference in the ability to adjust osmotically if present; 
could account for the difference between non-VAM and VAM plants in stomatal and 
photosynthetic behaviour. The subject of VAM associated physiological changes is 
to be emphasized as it is essential for proper assessment of the potential benefits of 
inoculating crops with VAM fnngi. 

REFERENCES 

Hsiao, T. C. 1973. Plant response to water stress. Ann. Rec. PI. Physiol. 1<\ : 519-570. 

Nelson, C. E., Safir, G. R. 1982. The water relations of well watered mycorrhizal and non- 

mycorrhizal onion plants. J. Am. Soc. Hort. Sci. 107 : 271-274. 
Goyal, A., Gupta, R. K. 1985. Carbon flux in the phytosynthetic and photorespiratory metabolites 

at different leaf water potentials in rice Oryza satlva L. var. Jaya. J. Nuc. Agr. Biol. 

14 : 4-7. 
Allen, M. F., Boosalis, M. G. 1983. Effects of two species of vesicular-arbuscular mycorrhizal 

fungi on drought tolerance of winter wheat. New Phytol. 93 : 67-76. 



C 62" ] 



Effect of soil degradation on soil microbes, symbionts and their 
activities 

D. K. JHA, S. KSHATTRIYA, G. D. SHARMA ANA R R. MISHRA 
Department of Botany, North-Eastern Hill University Shillong-793 014 

Soil degradation is defined as any change in physical and chemical properties 
of soil, which reduces the productivity of site. Soil of the N.E. region has very poor 
nutritional status. Most of the nutrient capital of site is concentrated in the organic 
horizon, which takes years to accumulate and enrich the upper soil layers. Besides, 
soil organic matter also acts as rooting substrata and supports natural regeneration. 
It also provides energy source for microorganisms that contribute to release of 
nutrients. So, any change in this organic layer may lead to the formation of fragile 
ecosystem. In N.E. region of India, where slash burn agriculture is rhe most 
prevalent form of agriculture, it desrroys the organic layer and thus slows down the 
process of succession. 

Soil is considered to be the most dynamic site of biological interactions. 
Microbial population and their activities in soil can be regulated by its physicoche- 
mical characters (Tiwari et a!., 1987). Climate and vegetation are other two parame- 
ters which can affect the population and activity of soil microbes (Mishra and 
Sharma, 1977). Wohlrab et al. (1963) demonstrated that there is a shift in the 
species composition of soil microbes which parallels pioneer vegetational succession. 
There are, however, few studies on effect of disturbance on soil micro-fungal popu- 
lation (Donald and Whittingham, 1978) but the effect of same on microbial activities 
is yet to be studied. This study aims to analyse the changes in the microbial 
population and their activities due to soil degradation. 

For this study two forest stands, showing different stages of disturbances were 
selected at Byrnihat (100m MSL, latitude, 26°00" N, longitude 91°50") about 80km 
from Shillong. Soil was collected randomly from five different places from a depth 
of 0- 10cm from each site separately. Soil fungi and bacteria were isolated by dilution 
plate method where as for the isolation of endomycorrhizal spores Gerdemann and 
Nicolson's (1963) wet seiving and decanting method was followed. The intensity of 
mycorrhizal infection was assessed by the morphometric technique. Dehydrogenase 
activity was measured by TTC reduction technique of Casida (1977). 

The soil fungal population showed an almost similar seasonal trend in both 
the forest stands. However, the less degraded site harboured more population than 

[ «"] 



more degraded one. The peak was observed in May in both the cases. In case of 
bacteria, two peaks i. e. in May and September were recorded. The minimum 
bacterial population was observed in July. The less degraded forest stand had more 
bacterial population than its more degraded counterparts. Altogether 25 fungal 
species were isolated. In general, almost all the fungal species were isolated from 
both the forest stands except few species present only in less degraded site. Penicillium 
chrysogenwn was dominant in both the cases. 

The plant species inhabitating more degraded site were more mycotrophic than 
those on less degraded ones. No marked seasonality was observed in the intensity of 
infection. However, the less degraded site harboured more spores than more 
degraded ones. Maximum spores were counted during winter months while less 
during summer. 

The dehydrogenase activity too was more in Jess degraded forest stand 
than in more degraded one. Maximum dehydrogenase activity was measured in 
May. 

The marked seasonality in microbial may be attributed to soil organic matter 
content, moisture, temperature and pH (Tiwari et al., 1987). Low microbial counts 
in July may be dus to washing away of soil microflora. Maximum dehydrogenase 
activity in May may be attributed to higher bacterial number and increased moisture 
level (Baruah and Mishra, 1984). From the results it was evident that soil degrada- 
tion had an adverse effect on microbial population and their activities. High 
microbial population in less degraded site may be attributed to high organic carbon 
added by high litter fall and high moisture content owing to closed canopy with trees 
and herbaceous species which have helped in conservation of soil moisture and less 
penetration of light to ground. Thus it might have also prevented the loss of organic 
matter. The extensive degraded site was dominated by the herbaceous weedy 
pioneer species with sparse canopy. The change in population and activities may 
also be due to change, in resource quality of litter added by different species compo- 
sition of sites. More mycotrophy in plants growing at more degraded site may be 
explained in terms of the fibrous roat nature, of the weedy species, low nutrient status 
of soil and availability of more light required for photosynthesis and increased root 
contacts. Low VAM count in more degraded site can be attributed to soil distur- 
bance which reduced the mycorrhizal propagules (Reeves et al., 1979). 

REFERENCES 
Baruah, M., Mishra, R. R. 1984. Dehydrogenase and urease activities in rice field soils. Soil Biol. 

Biochem. 16 : 423-424. 
Casida, L. E. 1977. Microbial metabolic activity in soil as measured by dehydrogenase determina- 

. tion. Appl. Environ. Microbiol. 34 : 630-636. 
Donald, T. W., Whittingham, W. F. 1978. Comparison of soil microfungal population in disturbed 
and undisturbed forests of northern Wisconsin. Can. J Boi. 56 : 1702-1709. 

t 64 ]: 



Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal endogone species extracted from 
soil by wet sieving and decanting. Trans Brit. Mycol. Soc. 46 : 235-244. 

Mishra, R. R., Sharma, G. D. 1977. Ecology of soil fungi : population variation in relation to 
varying cover vegetation and soil factors. Sydowia Ann. Myco. Ser II 30 : 1-6. 

Reeves, F. B , David, W., Moorman, T , Kiel, J. 1979. The role of endomycorrhizae in revegetation 
practices in the semiarid west I. A comparison of incidence of mycorrhizae in severely 
disturbed vs. natural environments- Amer. J. Bot. 66 : 6013. 

Tiwari, S. C, Tiwari, B. K. Mishra, R. R. 1987. Temporal and depth-wise variations in dehydro- 
genase and urease activities and bacterial population in pine apple plantation soils. Proc. 
Indian Natn. Sci Acad B. 53 : 173-176. 

Wohlrab, G. R. Tureson, W., Olmstead, C. E. 1963. Fungal population from early stages of 
succession in Indianna dune sand. Ecology 44 : 1734-1740. 



I 65 ] 



Effect of pH on the growth of ectomycorrhizal fungi in vitro 

B. N. JHA, G. D. SHARMA AND R. R. MISHRA 
Department of Botany, North-Eastern Hill University, Shillong-793 014 

Ectomycorrhizal association is important for the establishment and growth of 
pine seedlings. Several criteria have been used in selection of ectomycorrhizal fungi 
for their inoculation in tree nurseries (Trappe, 1977). Some experiments on pH for 
ectomycorrhizal fungi indicate that optimum growth of most of the fungi occurred 
between the pH range 4.5 to 5.5, but these can be affected by other factors like; 
duration of growth (Modess, 1941; Norkrans, 1950); nitrogen source (How, 1940) 
and salts (Norkrans, 1950). 

Information on the behaviour of mycorrhizal fungi at different soil reactions 
is very less (Hung and Trappe, 1983). Therefore, the present experiment was 
carried out to assess the growth of ectomycorrhizal fungi in response to different pH. 

The ectomycorrhizal fungi namely, Laccaria laccata, Collybia radicata, Rhizo- 
pogon luteolus and Pisolithus tinctorius were isolated from sporocarps and roots of 
Pirmskesiya in earlier studise (Sharma, 1981). These fungi were grown on modified 
Melin Norkran's (MM N) medium. Five levels of pH i.e. 3, 5, f, 7 and 8 were 
maintained on MMN solid and liquid media with the help of .IN HC1 and .IN 
NaOH solutions. 

L. laccata showed maximum colony growth at pH-5, while its dry weight was 
maximum at pH-7. C. radicata and R. luteolus produced maximum growth at pH-6. 
P. tinctorius exhibited better colony spread at pH-7 and dry weight at pH-6. Colony 
growth of L. laccata and G. radicata was lowest in highly acidic condition (pH-3) 
whereas, R. luteolus was advearsely affected by a slight acidic condition (pH-5). No 
growth was obtained by P. tinctorius at pH-3. Production of dry weight by L. laccata, 
R. luteolus and P. tinctorius was less in highly acidic condition and by C. radicata in 
alkaline condition. Significant increased growth of L. laccata was observed at pH-5 
but showed very poor growth in alkaline conditions compared to other mycorrhizal 
fungi. In case of C. radicata and R. luteolus maximum growth was obtained at pH-6 
while, P. tinctorius showed better growth in alkaline condition. 

Interspecific variation in growth was noticed in all the pH conditions. R. 
luteolus exhibited a broad tolerance range for pH, while L. laccata was with narrow 
ecological amplitude. P. tinctorius showed some affinity with alkaline condition. 

[' 66 ] 



It has been observed that most of the fungi grew better at pH range of 5-6. 
Melin (1924) and Modess (1941) had also advocated the acidophilic nature of 
ectomycorrhizal fungi. P. tinctorius grew well at higher pH. It indicated that the 
fungi was able to grow in alkaline condition. Bokar (1959) has reported growth of 
ectomycorrhizal fungi at pH 8.3. In contrast R. luteolus showed its growth in 
extreme acidic condition. The selective ion uptake and production of organic acids 
by the mycelium may account to their variability in growth at different pH (Hung 
and Trappe, 1983). The organic acids of fungi may help in increasing the uptake 
of phosphorus either through chelating the metals or increasing the phosphatase 
activity. However, growth of ectomycorrhizal fungi may also be assessed on the 
contents of nitrogen, phosphorus, temperature and soil moisture (Safir and Duniway, 
1982). Therefore, specificity of the strain to different pH may depend on its 
physiological demand for the ions in medium. 

Based en the study, it may be suggested that R. luteolus may be used as 
inoculum for pine under highly acidic condition, L. laccata and C- radicata jn 
medium acidic condition and P. tinctorius in alkaline condition to get their maximum 
benefit. 

REFERENCES 

Bokar, D. 1959. A mykorrhiza-gombak novekedese es a taplalo kozeg reakcioja kozotti kolcson- 

hatasok vizsgalata. Erdesz. Kutataso. 6 : 389-394. 
How, J E. 1940. The myccrrhizal relations of larch. I. A study of Boletus elegans Schum. in pure 

culture. Ann. Bot. 4 : 135-150. 
Hung, L. L., Trappe. J. M. 1983. Growth variation between and within species of ectomycorrhizal 

fungi in response to pH in vitro. Mycologia 75 : 234-241. 
Melin, E. 1924. Uber den Einfluss der Wasserstoffionehkonzentration auf die Virulenz der Wurzel- 

pilze von Kiefer und Fichte. Bot. Not. 19 : 38-48. 
Modess, O. 1941. Zur kenntnis der Mykorrhizabildner von, kiefer und Fichte. Symb. Bot. Upsal. 

5 : 1-147. 
Norkrans, B. 1950. Studies in growth and Cellulotic enzymes of Trlcholoma. Symb. Bot. Upsal. 

9 : 1-126. 

Safir, G, R., Duniway, J. M. 1982. Evaluation of plant response to colonization by VA-mycorrhiza 
fungi. B. Environmental variables fn : Methods and principles of Mycorrhizal Research, 
Ed. N. C. Schenck, American Phytopatho. Soc. St. Paul M. N., pp. 77-80. 

Sharma, G. D. 1981. Ecological Studies on mycorrhizae of Pine (P. kesiya). Ph.D. thesis sub- 
mitted to NEHU, Shillong. 

Trappe, J. M. 1977. Selection of fungi for ectomycorrhizal inoculation in nurseries. Ann. Rev. 
Phytopathol. 15 : 203-222 



C 67 ] 



Phosphate response curve of Leucaena inoculated with Gigaspora 
margarita 

M. S. BYRA REDDY, D. J. BAGYARAJ AND B. C. MALLESHA 

Department of Agricultural Microbiology, University of 

Agricultural Sciences. GKVK, Bangalore-560065 

Vesicular-arbuscular (VA) mycorrhizal fungi improve plant growth mainly 
through increased uptake of phosphorus from soil. Plants lacking root hairs are 
more dependent on mycorrhizae. Leucaena leucocephala (Lam.) de wit. has virtually 
no root hairs and is strongly mycorrhizal (Munns and Mosse, 1980). Recently it 
was found that Gigaspora margarita is one of the efficient VA mycorrhizal fungus for 
inoculating Leucaena (Bagyaraj et ah, 1989). Hall (1978) stressed that mycorrhizal 
inoculation experiments should be carried out using a series of phosphate fertilizer 
levels. It should tften be possible to select the fertilizer level at which the responses 
to inoculation can be optimised (Menge et ah, 1978). These kinds of experiments 
suggest the amount of P fertilizer that can be saved with mycorrhizal inoculation to 
produce the same amount of biomass. Therefore an experiment was carried out to 
determine the response of Leucaena, uninoculated and inoculated with Gigaspora 
margarita using super-phosphate and Mussorie rock phosphate at different levels (0, 
5, 10, 15, 20, 30 and 40 kg per hactare). The plants were harvested 75 days after 
sowing. 

The recommended level af phosphatic fertilizer for Leucaena is 20kg P/ha. The 
observations revealed that of the two sources of P, superphosphate is a better source 
producing higher shoot biomass compared to Mussorie rock phosphate, ihe results 
also showed that the shoot biomass production wjth the recommended level of P 
(when Mussorie rock phosphate was added as the source of P) was 7.22 g/plant. 
Nearly the same amount of shoot biomass was produced with half the recommended 
level of P when the plants were inoculated with Gigaspora margarita. When 
superphosphate was used as the source of P, the observations revealed that nearly 
75% of recommended P can be saved through inoculation with Gigaspora margarita. 

Nearly 50 to 75% of the phosphatic fertilizer application can be saved by 
inoculating Leucaena with the efficient VA mycorrhizal fungus, Gigaspora margarita. 

l[ 68 ] 



REFERENCES 

Bagyaraj, D. J., Byra Reddy, M. S., Nalini, P. A. 1989. Selection of an efficient inoculant VA 

mycorrhizal fungus for leucaena. Forest. Ecol. Manage. 27 : 81-85. 
Hall, I. R. 1978. Effects of endomycorrhizas on the competative ability of white clover. NZ. J. 

Agric. Res. 21 : 509-515. 
Menge, J. A., Labanauskas, G. K , Johnson, E. L. V., Piatt, R. G. 1978. partial substitution of 

mycorrhizal fungi for phosphorus fertilization in the greenhouse culture of citrus. Soil 

Sci. Soc. Am. Proc. 42 : 926-930. 
Munns, p. N., Mosse, B. 1980. Mineral nutrition of legume crops. In : Advances in Legume 

Science, Eds. R. J. Summerfield, A. H. Bunting, England, Univ. of Reading Press, 

pp. 115. 



Response of different cultivars of sorghum {Sorghum vulgare) to 
inoculation with Glomus versiforme 

MOHAN SINGH AND K. V. B. R. TILAK 
Division of Microbiology, Indian Agricultural Research Institute, New Delhi-1 10012 

Recent advances in agricultural technology particularly with the development 
of high yielding nutrient-responsive varieties of crops, have opened new vistas in crop 
productivity leading to green revolution in India. However, the yield of cereals per 
unit area remain low and variable because of many constraints including inadequate 
fertilization. Among the plant nutrients, phosphorus is the essential nutrient next 
to nitrogen in increasing crop production. Biological agents like vesicular-arbuscular 
(VA) mycorrhizal fungi if improve the efficiency of phosphorus uptake by plants, the 
increase in crop production could be possible without application of high levels of 
phosphate fertilizer. The beneficial response of wheat, barley, onion, maize and 
other crops to inoculation with VAM fungi have been well documented (Fitter, 
1985). 

The selection of efficient VAM fungal species, which can help in enhancing 
the phosphorus supply and the choice of genotype which can get maximum benefits 
of the VAM association are the two vital factors to improve the existing VAM-plant 
association. The present study deals with the response of different genotypes of 
sorghum (Sorghum vulgare L.) to inoculation with Glomus versiforme. 

A pot culture experiment was conducted using steam sterilized sandy-loam soil 
to evaluate the mycorrhizal dependency of five different sorghum genotypes viz, 
CSH-9, CSH-5, PC-9, PC-6 and PC-23. There were two treatments for each 
variety-un-incoulated control and inoculated with Glomus versiforme (Daniels and 
Trappe). The experiment was laidout in a complete randomized block design with 
six replications. Uniform basal dose of nitrogen was applied in all pots in the form 
of urea at the rate of 60 kg N ha -1 . 

Inoculation with VAM fungus was done by the layering method (Jackson 
et al., 1972). The inoculum (20 g pot -1 ) consisting of infected root segments 
(50-70%) and chlamydospores (100-150 spores per 10 g soil) was placed at a depth 
of 3-5 cm in the pot. Sorghum seeds were sown just above the inoculum layer. The 
uninoculated control pots received the washings of inoculum soil sieved through 45/t 
filter to assure similar microbial papulation in all treatments. 

I W ] 



The plants were cut at 60 days of growth just 2-3 cm above the base and 
allowed to exude for 3 min. The exudate was collected with a syringe in aid washed 
tubes which were kept in an icebath. The phosphorus in the xylem sap was determi- 
ned using ascorbic acid as reducing agent (Chen et ah, 1956). 

The mycorrhizal efficacy was calculated using the following formula : 

Mycorrhizal efficacy : 100 (1 _ Non-mycorrhizal plant weight 
Mycorrhizal plant weight ' 

Response of different genotypes of sorghum to inoculation with G. veriforme 
was highly variable. The interaction between the endosymbiont and plant cultivars 
was significant. Among the 5 genotypes, the growth promoting ability of G. versiforme, 
measured in terms of mycorrhizal efficacy varied from 24-43 per cent. The maximum 
increase was observed in variety PC 23, followed by CSH-5, CSH-9, PC-9 and PC-6 
varieties of sorghum. 

Total phosphorus uptake by the mycorrhizal plants of different genotypes was 
significantly higher than the control plants. The phosphorus uptake by plants due 
to inoculation with G. versiforme among the various cultivars varied from 45-136 per 
cent, the maximum increase being observed in cultivar PC-9, although this cultivar 
did not register maximum mycorrhizal efficiency. Mycorrhizal infection has been 
reported to alter biochemical and physiological activity of plants (Carling aod Brown, 
1980) and these processes are more likely to be controlled by the host. Thus 
mycorrhizal efficiency in terms of phosphorus uptake and its utilization may be under 
the influence of host genome. The results are in agreement with the observations 
made in wheat (Azcon and Ocampo, 1980) and pearlmillet (Krishna et ah, 1985). 

Total phosphorus concentration in the xylem sap of mycorrhizal plants was 
usually higher than the non-mycorrhizal plants. However, in the case of PC-23, the 
concentration of P in the xylem sap of both mycorrhizal and non-mycorrhizal plants 
was similar. Inoculation with G. versiforme brought in significant increase in the 
concentration of inorganic phosphorus of xylem sap collected from varieties CSH-9, 
CSH-5 and PC-9. However, similar increase was noticed in PC-6 and PC-23 
varieties. The organic P concentrations in xylem sap of different cultivars was not 
significantly affected due to mycorrhizal inoculation in case of FC-9. 

Growth and phosphorus uptake of sorghum {Sorghum bicolor) on steam- 
sterilized, phosphorus deficient soil was improved by the soil inoculation with VAM 
fungus, Glomus versiforme. Among the 5 sorghum genotypes viz. CSH-9, CSH-5, 
PC-9, PC-6 and PC-23, tested for their mycorrhizal dependency, PC-23 produced 
maximum mycorrhizal efficiency and phosphorus uptake with G. versiforme. 

1:1"'. ] 



REFERENCES 

Azcon, R., Ocampo, N. A. 1980. Factors affecting the vesicular-arbucular infection and mycorrhiza I 

dependency of thirteen wheat cultivars. New Phytot. 87 : 677-685. 
Carling, D. E., Brown, M. F. 1980. Relative effects of vesicular mycorrhizal fungus on the growth 

and yield of soybeans. Soil Sci. Soc. Am. Proc. 44 : 528-532. 
Chen, P. S., Toribara, t. Y., Warner, H. 1956. Microdetermination of phosphorus. Ana. Chem. 

28 : 1756-1758 
Fitter, A. H. 1985. Functioning of vesiculaf-arbuscular mycorrhizae under field conditions. New 

Phytol 99 : 257-265. 
Jackson, N. E., Franklin, R. E., Miller, R. H. 1972. Effect of vesicular-arbuscular mycorroizal 

fungi on growth and phosphorus content of three agronomic crops. Soil Sci. Am. Proc. 

86 : 64-67. 
Krishna, K. R., Shetty, K. G., Dart, P. J., Andrews, D. J. 1985. Genotype dependent variation in 

mycorrhizal colonization and response to inoculation of pearlmillet. PI. Soil 86 : 113-125. 



II 72 ] 



Influence of vesicular arbuscular mycorrhizae on the photo synthesis 
and photo respiration of sweet potato (Ipotnoea, batatas) 

V. P. POTTY AND P. INDIRA 
CTCRI., Sreekariyam, Trivandrum-17 

Role of VAM on the photosynthesis and photo respiration in sweet potato 
was studied under pot culture condition. The infected cuttings of sweet potato 
(Kanjangad) were maintained under three phosphorus regimes. Under low and 
medium phosphorus levels growth of mycorrhizal plants were higher than that of 
non-mycorrhizal. The rate of CO a fixed by the mycorrhizal plant was to the tune of 
22.27 ppm C0 2 . Sqm. -1 Sec. -1 which was 33.3% increase over control at half 
recommended dose of phosphorus and was significantly higher than that of non- 
mycorrhizal and mycorrhizal plants receiving higher phosphorus level. The study 
showed that root to tuber ratio was narrow when compared to non-mycorrhizal and 
mycorrhizal plants receiving higher dose of phosphorus. There was an increase 
in leaf area and dry matter to the tune of 6% and 17.5% respectively in mycorrhizal 
plants. High rate of CO a fixation in the leaves of mycorrhizal plants might be an 
inherent mechanism of the host plant to compensate the carbon drain from the plant 
to mycorrhiza in the initial stages and ultimately resulting into the changed root 
to tuber ratio, in favour of plant. 



t 73 ] 



Effect of foliar application of urea on nitrogen metabolism of 
mycorrhizal moong plants under varying phosphorus levels 

SHASHI THAPAR, B. S. SEKHON, AMARJIT ATWAL AND RATTAN SINGH 
Deptt. of Biochemistry, Punjab Agricultural University, Ludhiana 

Supplementary N provided by foliar spray has been shown to be rapidly 
absorbed and assimilated by leaves resulting in increased growth of seedlings and 
high seed protein of mature barley plants (Turley and Ching, 1986 . The present 
investigations were carried out to study the effect of foliar sprayed urea during pod 
filling on nitrate reductase and glutamine synthetase activities and content of urea, 
ammonia, amino acids, soluble proteins, sugars and chlorophyll in leaves of mycorr- 
hizal and non-mycorrhjzal moong plants grown under different P levels in a pot 
experiment. 

Moong (Vigna radiata L. cv. ML-131) seeds were sown in the pots each 
containing 5 kg sterilized soil. The P treatments in the absence of mycorrhizal 
inoculation were : Control - P , \0pg P g~ l soil - P 10 , 20/tg P g- 1 soil - P 20 and MP , 
MPio, MP 80 in the presence of mycorrhizal inoculation. Potassium dihydrogen 
phosphate was used as the P source. All the pots received 10 /ig KN0 3 -N g- 1 soil 
at the sowing time along with Rhizobium (strain MA 7) inoculation to seeds. For 
mycorrhizal inoculation, the spore suspension prepared from the soil containing 
275-300 spores of Glomus fasciculatum per 100 g, was mixed 5 cm below the soil 
surface. Four plants per pot were maintained. Sixty three days after sowing, the 
leaves were sprayed with 100 fig ml -1 urea-N in 0.1% Triton X— 100. The plants 
which received only 0.1% Triton X— 100 spray, served as control. The plants were 
harvested at 4 DAA for the analysis of various biochemical parameters in fully 
expanded young leaves. 

In vivo NR activity and GS activity were assayed as described earlier (Sekhon 
et al, 1987). In the enzyme extract prepared for GS, soluble proteins were estimated 
by the method of Lowry et al. (1951). The proteins in the above extract were 
precipitated using 20% TCA. After neutralization with NaOH, in this extract sugars, 
total amino acids, ammonia and urea concentrations were estimated (Dubois et al., 
1956; Lee and Takahashi, 1966; Watt and Crisp, 1954; yuen and Pollard, 1982). 
Leaf chlorophyll was extracted with 96% (v/v) ethanol and determined (Johnston 
et al. , 1984). The data represent the mean of triplicate analysis. 

From the studies it can be concluded that the increase at P and P 10 levels in leaf 
nitrate reductase, glutamine synthetase activities and ammonia concentration in 
mycorrhizal plants is equivalent to P 20 level in non-mycorrhizal plants. 

t 74 ] 



The increased glutamine synthetase activity and total amino acid concentra- 
tion suggest that foliar applied urea gets assimilated into the amino acids. 

Mycorrhizal plants had lesser concentration of sugars but more chlorophyll 
compared to nonmycorrhizal plants, due the foliar urea spray. 

REFERENCES 

Dubois, M., Gills, K. A., Hamilton, J. K., Rebers. P. A., Smith, F. C. 1956. Colorimetric 
method for determination of sugars and related substances. Anal. Chem. 28 : 350-356. 

Johnston, M., Grof, C. P. L., Brownell, P. F. 1984 Effect of sodium nutrition on chlorophyll a/b 
ratio in C 4 plants. Aust. J. Plant Physiol. 11 : 325-332. 

Lee, Y. P., Takahashi, T. 1966 An improved colorimetric method for determination of amino 
acids with the use of ninhydrin. Anal. Biochem. 14 : 71-77. 

Lowry, O. H, Rosebrough, N J., Farr, A. L., Randall, R.J. 1951. Protein measurement with 
folin phenol reageat. /. Biol. Chem. 193 : 265-290. 

Sekhon, B. S., Thapar, S., Dhillon, K. S., Singh, R. 1987. Effect of applied nitrogen on N a - 
fixation, assimilation of nitrate and ammonia in nodules of field grown moong (Vigna 
radiata). Ann. Bot. 60 : 613-620. 

Turley, R. H., Ching, T. M. 1986. Physiological responses of barley leaves to foliar applied urea- 
ammonium nitrate. Crop Sci. 26 : 987-993. 

Watt, G. W., Crisp, J. D. 1954. Spectrophotometry method for determination of urea. Anal, 
Chem. 26 : 452-453. 

Yuen, S. H., Pollard, A. G. 1982. The determination of nitrogen in agricultural materials by the 
Nessler regeant. 1. Preparation of the regeant. /. Set. Food Agric. 3 : 441-447. 



t ?5 J 



Biological interactions between VA mycorrhizal fungi and other 
beneficial soil organisms 

D. J. BAGYARAJ 

Department of Agricultural Microbiology, University of Agricultural Sciences, 
Bangalore-560 065, India 

Of the various microorganisms colonizing the rhizosphere, vesicular arbuscuJar 
mycorrhizal (VAM) fungi occupy an unique ecological position as they are partly 
inside the host and party outside the host. The present position of VAM research 
pointed out that more investigations are needed on the biological interactions between 
VAM fungi and beneficial soil organisms, and their effects on plant growth (Linderman, 
1988). In this paper the different aspects of biological interactions between VAM 
fungi and other beneficial soil organisms are considered. 

Most of the studies on YAM-Bhizobium interaction suggest that colonization 
with efficient endophytes significantly improve P nutrition and consequently nodula- 
tion and nitrogen fixation (Hayman, 1986). While the principal effect of mycorrhiza 
on nodulation is undoubtedly phosphate mediated, mycorrhiza may have other 
secondary effects. Such potentially limiting factors may include supply of photo- 
synthate, trace elements and plant hormones. Recent field studies have shown great 
advantages of dual inoculation by the two symbionts. The method of application 
of inoculum would also pose a problem as most of the grain and forage legumes are 
directly sown in the field. Perhaps an immediate application could be in forestry as 
some leguminous tree species like Acacia, Robinia, Leucaena and many others could 
be preinoculated with selected rhizobia and mycorrhiza in the nursery to produce 
nodulated mycorrhizal seedlings before planting out in the field during the affores- 
tation programmes. 

Bagyaraj and Menge (1978) studied the interaction between Azotobacter 
chroococcttm and the VAM fungus Glomus fasciculatum in tomato and found a 
synergistic effect on plant growth. Mycorrhizal colonization increased the A. 
chroococcttm population in the rhizosphere which was maintained at a high level for 
a longer time and A. chroococcum enhanced colonization and spore production by 
the mycorrhizal fungus. Similar interactions have also been observed between other 
free living nitrogen fixers and VAM by other workers. Sometimes the beneficial 
effect on plant growth from free living nitrogen fixing organisms was attributed to 
hormone production rather than, or in addition to, nitrogen fixation. 

Many soil microorganisms solubilize unavailable forms of P and these bacteria, 
called 'phosphobacteria' have been used as 'bacterial fertilizers'. Interaction studies 

[ 76 ] 



showed that phosphate solubilizing bacteria survived for a longer period in the 
rhizosphere of mycorrhizal roots (Linderman, 1988). The phosphate solubilizing 
bacteria rendered more P soluble, while mycorrhiza enhanced P uptake thus with 
combined inoculation there was a synergistic effect on P supply and dry matter 
production. Phosphate solubilizing bacteria also produce hormones and vitamins. 

Krishna et al. (1982) studied the interaction between the VAM fungus G. 
fasciculatum and the actinomycete Streptomyces cinnamomeus introduced into the 
rhizosphere of finger millet. Simultaneous inoculation with both the organisms had 
an antagonistic effect on each other each suppressing the growth and multiplication 
of the other in the rhizosphere. Interaction between the actinomycete Frankia and 
VA mycorrhiza was found to be synergistic with consequential benefit on plant 
growth (Gardner, 1986). 

Certain 'companion fungi' live in close association with VAM fungi. In a 
field trial with pasture in a low P soil, one isolate of the companion fungus gave a 
3-fold increase in dry matter, equivalent to an application of 250 kg/ha super- 
phosphate. These observations question whether the improved growth obtained by 
inoculating plants with roots and soil from a pot culture of VA endophytes is due to 
VAM fungus alone or a cumulative effect of the mycorrhizal fungus and the 
companion fungus. 

Epiphytic associations of an Azotobacter sp. with spores of G. fasciculatum 
have been observed. Pseudomonas sp. was found to be a common associate with 
VAM spores, and helped the mycorrhizal fungi in infecting the roots. The bacteria 
associated with different endophytes were even found to have a stimulatory effect on 
plant growth (Mosse, 1972). 

It should not be forgotten that rhizosphere is a complex region in the soil- 
plant interface with high micorobial activity. However, the results obtained so far 
with biological interaction studies between VAM fungi and other beneficial soil 
organisms are encouraging and indicate the need for strengthening research in this 
area. 

REFERENCES 

Bagyaraj, D. J., Mengs, J. A. 1978. Iateractioa between a VAM and Azotobacter and their effects 
on the rhizosphere microflora and plant growth. New Phytol. 80 : 567-573. 

Gardner, I. C. 1986. Mycorrhizae of actinorhizal plants. MIRCEN J. App. Microbiol. Biotech. 
2 : 147-160. 

Hayman, D. S. 1986. Mycorrhizae of nitrogen fixing legumes. MIRCEN J. App. Microbiol 
Biotech. 2 : 121-145. 

Krishna, K R , Balakrishu, A. N., Big/ar.ij, D. J. 1982. Interaction between VAM and Strepto- 
myces cinnamomeus and their effect on finger millet. New Phytol. 92 : 401-405. 

Linderman, R. G. 1988. Mycorrhizal interactions with the rhizosphere microflora : The mycorrhi- 
zosphere effect. Phytopathology 78 • 366-371. 

Mosse, B. 1972. The influence of soil type and Endogone strain on the growth of mycorrhizal plants 
in phosphate deficient soils. Rev. Ecol. Biol. Sol. 9 : 529-537. 

[ 77 ] 



Interactions of mycorrhizal fungi with root pathogen of cocoa 

A. H. CHULAN, G. T. SHAJI AND Z. A. CHRISTINE 

Jabatan Sains Tanah Universiti Pertanian Malaysia-43400 UPM 

Serdang, Selangor, Malaysia 

This study evaluates the feasibility of using the mycorrhizal fungi as a biologi- 
cal control agent against one root pathogen of cocoa, Ganoderma pseudoferreum 
which causes the "Red root" disease. This disease, though not as destructive as the 
vascular streak dieback, is nevertheless rampant in most cocoa plantations of 
Malaysia. 

Three-week old cocoa seedlings from the Sabah hybrid were subjected to the 
following treatments : (1) pre-inoculation with VAM fungi at age 3 weeks followed by 

inoculation with the pathogen at age 11 weeks, (+M +P); (2) simultaneous 

inoculation with both VAM and pathogen at age 11 weeks (+M+P); and (3) inocul- 
ation with pathogen only at age 11 weeks, (+P); and (4) without any inoculation 
(-M-P). 

The effect of the mycorrhizal fungi on host-pathogen relationship is an indirect 
one (Dehne, 1982). This is achieved by physiological alterarion of the host or by 
competition for space or host resources (Schenck, 1981). Such an effect is evident 
from the present study, where preinoculation of the cocoa seedlings with the VAM 

fungi (+M +P), significantly reduced the pathogenic fungal infection of the 

cocoa roots. Ten per cent of the roots of the +P seedlings succumbed to Ganoderma 
infection, while in the +M+P seedlings, infection was reduced to 5%. The — M— P 
plants did not show any infection. 

Tissue analysis done on the seedlings from the various treatments, indicated 
significant difference in the levels of Ca, K and P. The concentrations of these 

elements, in decending order are as follows : (+M +P) > (+M+P) > 

(— M— P) > (+P). Increase in P content of mycorrhizal roots had been shown to 
be responsible for reduced membrane permeability, with a resultant decrease in 
exudation out of roots (Graham, 1988). This simultaneously resulted in reduced 
soil borne diseases. Presence of high Ca f ion content in mycorrhizal tissues seemed 
to inhibit the pectolytic activity of the pathogen (Marschner, 1986). 

C 78 ] 



REFERENCES 

Dehne, H. W. 1982. Interactions between vesicular-arbuscular mycorrhizal fungi and plant 

pathogens. Phytopathology 72 : 1115-1119. 
Graham, J. H. 1988. Interactions of mycorrhizal fungi with soilborne pathogens and other 

organisms : an introduction. Phytopathology 78 : 365-366. 
Marschner, H. 1986. Mineral nutrition of higher plants. Academic Press Inc., London, 

pp. 372. 
Schenck, N. C. 1981. Can mycorrhizae control root disease ? Plant Disease 65 : 231-234. 



[ 79 ] 



Biotechnology for mass production of VA mycorrhiza inocula 

S. N. SINGH 
BAIF Development Research Foundation, Wagholi, Pune, India 

Biotechnology encompasses many facets of the management and manipulations 
of the biological systems. It embodies recent research in the field of Cell Biology. 
Recombinant DNA, Molecular Genetics and the related fields such as life science 
appears to be laying the groundwork for important technological development. The 
resulting technological take-off stage is being launched with all possible efforts and 
sincerity from Government of India in all the sphere of Science and Technolgy. 
These are likely to have a major impact on varieties of economic activities involving 
food, biochemistry, pharmaceuticals, biology, energy and environment. There are also 
likely to be significant industrial application through new products, new processes 
and methodologies. This type of direct participation in assessing the implication cf 
'new-biology' for it's programmes and priorities for taking-up biotechnological 
development programmes in the field of land management. Infusion of the manage- 
ment science with skill to manage the "LAND CARRYING CAPACITY" for food 
production and to sustain threat for environment and ecology. Thus in this regard 
'bioferfiJizer' is getting importance as widely accepted low cost input in agriculture, 
agro-forestry, wasteland development and ecology. Scientists, Extension Workers 
. and Planners are looking to this for exploitation for increasing crop production in 
agriculture. Scientists are unfolding the mysterious useful characteristics of microbes 
in the rhizosphere soil. Vesicular Arbuslar Mycorrhiza (VAM) is one to it's effect. 

In India agriculture and agro-forestry constitute potential rosources in making 
ru^al economy suitable for development. Tn agriculture, continuous cropping 
practiced on land is resulting into depletion of major soil nutrients such as Nitrogen, 
Phosphorous and Potash. These major nutrients need to be replenished to avoid 
any adverse effect on plant growth and subsequently on yield of the crops. 

Phosphate is one of the major nutrients required for plant growth. However, 
lack of phosphate in many tropical soils is one of the most serious constraint in plant 
growth. 

Dr. B. Mosse in 1957 demonstrated for the first time the importance of 
Vesicular Arbuscular Mycorrhiza in phosphate uptake. It is also established fact 
that zinc, copper and sulphur uptake is also improved in the pesence cf Vesicular 
Arbuscular Mycorrhiza. In addition to above, most important role of VAM is in 

[ 80 '] 



increasing plant resistance to drought conditions, protection against soil borne 
diseases, improving plant establishment and positive effect on soil aggregation thus 
contributing to soil erosion. 

Incorporation of these useful micro-organisms as biofertilizers to supply essential 
nutrients to cultivated crops especially under-intensive cropping conditions and 
unassured rainfall areas can help in successful sustainance type of agriculture primarily 
because they are low cost inputs. About 70 to 75% of the cultivated area in agri- 
culture comes under rainfed conditions, of this neary 50% is under unassured rainfall 
conditions. Crops such as legumes are grown mostly under unassured rainfall 
conditions with limited agronomical practices and no organic nutrient supply. 
Rhizobium biofertilizers have specific important role in increasing crop productivity 
in legume crops. 

Deforestation and degradation of forest areas have seriously affected atmos- 
phere and ecology. Due to this nearly 1200 crore tonnes of top soil is washed away 
every year having potential to produce 40 to 50 metric tons of food grains. As per 
tecent surveys hardly 10 to 11% land has now remained under worthy forests. Trees 
on 1.5 M. hectares of area of land are being illegally cut down every year resulting 
into ecological imbalance. 

Vesicular Arbuscular Mycorrhiza is specifically important for plantation crops 
of commercial value and free species important in agro-forestry, wasteland develop- 
ment programmes. Here usefulness of VA mycorrhiza is successful in plant 
establishment on topical soils which are deficient in phosphate and characterized by 
high inbuilt temperature due to low moiture, no irrigation and erosion problems. 

Thus, owing to these prolems in increasing productivity in agriculture develop- 
ment of biofertilizers making use of the beneficial organisms such as Rhizobium and 
VA mycorrhiza is timely and just. 

BAIF is a development research foundation engaged in socio-economic 
transformation of rural masses and laying emphasis on the development and appli- 
cation of appropriate teconologies for harnessing benefits through increased 
productivity. It's approach to rural development embodies efforts at improving the 
existing natural resource as available to the rural population and thereby creating 
means of gainful self-employment at the grassroot level. Among the various 
instruments which can come handy for such measures the use of beneficial micro- 
organisms in increasing productivity in agriculture stands out importantly. 

By virtue of the experience of working in rural areas, BAIF has recognized 
the need for creating a perennial source of income to farm families. Low productivity 
in agriculture is due to the in-appropriate management to the natural resources such 

[ 81 ] 



as land, water, vegetation and livestock available to the farmer. In view of this, 
BAIF has devised suitable models for optimum utilization of the land which is 
important among these resources. 

Agro-forestry is one to its effect which promises to be a vitaJ land-use 
alternative for our rural economy. As Agro-forestry ensures income accruing from 
both agricultural and forest commodities where the prices of the products enhanced 
by agro-forestry are gradually on the rise compared to the prices of agricultural 
commodities. 

BAIF is operating agro-forestry and wasteland development programmes in 
rural areas. The comparative advantage of these programmes are for the marginal 
and rainfed land areas where productivity is low and cultivation is at the risk of the 
vagaries of the monsoon. As such these lands are deficient in the phosphate content, 
which is one of the major nutrients required in successful establishment and growth 
of the plant. Being marginally productive replenishment of the phosphate to the 
soil through chemical fertilizers is also not been done adequately as it is not an 
economically feasible proposition. Owing to these factors, lhs soils are causing 
serious constraints for plant growth. 

However, it has been the experience at BAIF that on arid, shallow and 
unproductive soils plantation of agro-forestry tree species such as subabul (Leucaena 
leucocephala) can also be established successfully to produce fodder and fuel while in 
the process of carrying out soil amoelioration. In establishing such successful 
plantation a vital supporting role was provided by Rhizobium cultures. BAIF has 
taken-up a research programme on isolation, characterization and mass production of 
efficient strains of nitrogen fixing bacteria in relation to important multi-purpose 
tree species suitable for agro-forestry and wasteland development. 

In view of the experience, BAIF believes that biofertilizer technology consti- 
tutes a complentary and supplementary source of nitrogen nutrient supply in the input- 
intensive agriculture. This technology benefits small and marginal farmers who stand 
in immediate need of the low cost input to increase productivity in grains, legumes, 
forages, forestry and horticultural crops. Accordingly, BAIF has been involved in 
largescale production and distribution of adequately standardized cultures of micro- 
organisms, such as 'Rhizobia' which constitutes biofertilizers suitable for selected 
leguminous crops. BAIF is now exploring mycorrhizal potentials which is an 
important and responsive part of environment for plant nutrition, growth improve- 
ment, successful afforestation and land reclamation programmes. However, lack of 
massive inoculum is a bottleneck in the technological transfer of knowledge to grass- 
root level. Hence, at this stage, the standardization of largescale production 
technology and distribution of viable inoculum at the field level in the tropical 
countries is timely and just. 

[ 82 ] 



BAIF has undertaken a project on Development and Standardization Produ- 
ction Technology of VA Mycorrhiza Inocula. 

General objective of the project is to develop the mass production technology 
for VA Mycorrhiza and it's production methodology and delivery system. 

VA Mycorrhiza inoculum, it's mass production and application in the field 
for successful establishment of agricultural crops and forest tree species is gaining 
much importance. Considering the need of this lowcost agricultural input in culti- 
vated crops, agro-forestry and wasteland development programmes, the lack of 
massive inoculum is an obstacle coming in the way of largescale production of VA 
mycorrhizal fungi. The development of large quantities of pure inoculum free from 
pathogen and with high infective propagule numbers is situated at the cutting edge 
of the advances of knowledge on the use of biofertilizers. Achievement of goal of 
mass production of pathogen free endomycorrhizal inoculum will make the core of 
a network permitting transfer of technology to farmers, foresters, research and 
extension workers at the nursery and the farm level. 

It is more likely that climatic and edaphic factor rather than host specificity 
will determine successful introduction of VAM fungal species into a given agricultural 
situation. In the selection of an efficient strain, problem in comparing performance 
of fungal strain lies in the lack of standardization of experimental inocula. Various 
parameters are used in comparing different VAM fungi which are as initial inoculum- 
concentration, spore viability, or contaminate micro-organisms in the pot cultures 
rather than true differences in the efficiency of mycorrhiza formation and function of > 
individual fungi. In this regard, we have screened few mycorrhizal fungi obtained 
from different parts of Maharashtra for inoculating their host plant which have shown 
encouraging results. Glomus species have proved efficient in the experimental trials 
undertaken on onion and sunflower crops. 

Mycorrhizal fungi are maintained and mass produced at pot cultures on 
suitable host plants, plant growth period of 2-3 months can give a large crop of 
mycorrhizal fungal spores to produce sizeable amount of inoculum. In the selection 
of the host plant important criteria followed are as under — 

—Host plant species suitable to agro-climatic conditions of the area 

— Host plants with thick root system for sizeable sporulation and infection 

— Annual in growth habitat 

— Adaptability to glasshouse conditions 

— Crops important as staple food, cash crop, forage crops etc. 

In the present studies considering the agro-climatic aspect, host plant species 
such as maize, sorghum, bajra, bahia grass, rhodes grass, anjan grass and varieties 

[ 83 ] 



of guinea grass as forage crops are tried for root infection in the inoculum 

production. These hosts being annual, densely populated and producing thick root 

system are much suitable and can be easily grown under glasshouse condition. All 

the host plants have shown positive results in the sporulation and infection to the -j^ 

root system. However, percentage of root infection in bahia grass is considerably ^ 

high (98.5%). Hence, bahia grass could be a possible host useful in largescale 

production of the inoculum. 

Selection of substratum is important from the point of view of its suitability 
as material enhancing growth of the host plants in the mass production process and 
as a carrier in effective delivery of viable undiminished count of spores, sporocarps 
and infected root segment upto the user's end. However, certain criterias need to 
be followed in the selection of substratum in mass scale production of the inculum. 
We have considered following criteria in the selection of suitable substate. 

— Substrate non-organic in nature to avoid deterimental effect on the inoculum 
— Light weight to ensure economy in transportation cost 
—Good water holding capacity 
—Less leaching of essential nutrients 
—Easy to be removed from roof surface 

Accordingly, in cur present studies following substrates are used in different 
proportions with each other (by volumes) J^t> 

— Soil : Sand (1:3) 
— Soilrite : Sand (1:3) 
— VermicuJite : Peat (4.3:1) by weight 
— Perlite : Soilrite (1:1) 

The host plants mentioned earlier are grown under laboratory conditions on 
the substrates using above combinations. In this study vermiculite and peat (4.3:1) 
and Perile and soilrite (1:1) have proved to be the best substrates considering growth 
of plant, sporulation, percentage infection and viability of the inoculum. Our results 
are comparable with the findings of the studies undertaken by Bagyaraj et al. at the 
University of Agricultural Sciences Bangalore on this aspect of selection of substrate. 

The handling of the inoculum for mass production and evaluation under 
greenhouse conditions for it's potentials will depend on the form of inoculum selected ^ 

and production methodology standardized accordingly. Literature describing inoculum 
required especially for largescale field use is rare however, most of the inoculations are 
carried out with inoculum prepared in the form of— 

[ 84 ] 



— Granular, structure where VAM inoculum is produced in polyprophylene basins 
containing plant roots, mycorrhizal spores and substrate 

— Pellets containing mycorrhizal inoculum and sedimentary clay 

We in our present studies have tried combinations of VA mycorrhizal 
spores, infected root segments and substrates of different kind such as sand, soil, 
soilrite, perlite, peat and vermiculite in different proportions by volume as 
mentioned above. Infected root segments of the host plant used to produce the 
inoculum are highly infective and can be preserved long under cold room (4°C) 
conditions and at pot culture, seedlings and field level to keep their infectivity. 
However, among the three types of VA mycorrhizal inoculum, namely pure fungal 
cultures, infected roots and infested soil/substrate, in the largescale production and 
delivery at field level, use of fungal culture will be difficult. Accordingly, production 
of large quantity of infected root segments of the host plants free of substrate can be 
effective providing more rapid growth stimulation than the spores. 

Freeze dried cultures could be one of the possible avenues in the standardization 
of forms of inoculum. BAIF has standardized freeze drying technology in 30 ml. 
glass vial of cultures, which prolongs shelflife and economises transportation cost. 
Work at BAIF on freeze drying of biofertilizers incorporating requisite cryo- 
protectives have given encouraging results in preservation of viability of organisms 
for a long period. The freeze dried material has been used to inoculate field grown 
plants. 
/ '**mC We have initiated work on lypholisation of infected root segments spray 

dried and packaged in autoclavable polypropylene bottles, adding sucrose and 
skimmed milk powder as cryoprotective. Freeze drying technology will also prove 
to be an effective methodology for the lypholised lnocula with micronutrient as 
reconstituted buffer application to locally available substrate and hence inoculation 
to the sub-soil in desired manner. Experiments are going and MPRC will be able 
to come out with this inoculum in near future after successful pot culture and field 
trials. 

In the process of mass production of the inoculum candidate, mycorrhizal 
strain selected on the basis of its performance in glass and plastic containers and 
with due quality control measures is used for preparing secondary inoculum. 

—These inoculums are prepared in plastic or concrete basins of size 0.5m 2 x25 cm. 
deep which can be easily sterilized. 

— Secondary inoculum is produced using candidate strain with suitable host plant and 
^ subtrate of non-organic nature. Several plants are seeded over a layer in the 

basins. 
— The whole subtrate including spores and infected roots is used to prepare a 

composite inoculum after due quality control tests. 

[ 85 ] 



—Pilot scale mass production is being undertaken in the growth room or production 
unit which will provide necessary arrangements for plants growth under controlled 
conditions, these include — 

— Light intensity of 15 Klux on the plants using fluorescent and incondescent lights. 

— Photometer to measure light intensity 

—Filtered air to maintain aseptic conditions 

— Maintenance of the humidity of the air not under 60% and not over 80% 

Temperature control to ± 10°C providing 25-28°C temperature for plant growth 
— Autoclavable plastic containers for production of the inoculum, arranged on 

racks in production room 

Considering magnitude of problem of low productivity in agriculture BAIF 
has devised suitable models for appropriate use of land in rural areas to generate 
gainful self-employment and increasing productivity in agriculture. Having developed 
an innovative technology of largescale production of Rhizobium biofertilizers, its 
effective system of packaging and field delivery, BAIF has now undertaken and 
gradually progressing wtth the objectives of this Project on Development and Standar- 
dization of Technology for Mass Production of VA Mycorrhiza Inocula. 

Application of mass production of inocula biotechnology, its proper handling 
and distribution of viable inoculum at the farmer's level through networking cf strong 
field force will support and give impetous to programme of agro-forestry, wasteland 
development and energy plantation in rural areas. 

VAM biotechnology facets are to be sudied unravelled considering the aspects 
of the physiology, plant and soil interaction, phosphate mobilisation by this fungus 
etc. which will benefit research workers, pJanners, decision makers, extension workers, 
technology transfer, linkmen and ultimate farmers of the country for betterment of 
ecology and environment of earth. 

Therefore mass production of VAM inocula at MPRC at BAIF, Pune is 
receiving and will continue to receive the feed back for effective application, economic 
benefits, practical problems and corrective measures in wider acceptance of this 
technology at grassroot level can use, this information for making improvements at 
various stages of research and production of inocula. 



t 86 ] 



Interaction of VA-mycorrhizae with beneficial soil microorganisms 

K. V. B. R. TILAK. 

Division of Microbiology, Indian Agricultural Research Institute, 

New Delhi-110012 

Root penetration by VAM fungi is affected by several factors of different 
origin. Among which soil bacteria appear to be involved (Mosse, 1981). Such an 
enhancement of VAM formation, by selected microorganisms inoculated from pure 
cultures has also been reviewed (Barea and Azcon-Aquilar, 1982). 

Microbial interactions in the mycorrhizosphere of VA-mycorrhizae have been 
reviewed (Linderman, 1988). Interactions related to nutrient cycling have been 
described for nitrogen fixing bacteria, nitrifying bacteria, phosphate solubilizing 
bacteria and many other microorganisms. 

Bagyaraj and Menge (1978) found that inoculation with Azotobacter 
chroococcum or P-solubilizing bacteria in addition to a VAM fungus resulted in a 
synergistic host response. They concluded that the production of phyto hormone or 
growth regulators by these microbes might have had a greater effect on plant growth 
than small increase in N or P availability. Brown and Carr (1984) also reported 
improved growth and yield of lettuce plants in both sterile and unsterile soils when 
they were simultaneously inoculated with VAM endophytes and Azotobacter 
chroococcum. For cereal roots infected with Azospirillum and a VAM fungus, both 
endophytes are present in the same cortical region of the root making it possible to 
have direct interactions between the three symbionts which could range from 
enhancement of growth to competition for photosynthates. Interactions between 
Azospirillum and VAM fungus relative to the growth response of sorghum have been 
examined (Pacovsky and Fuller, 1985). Synergistic effect of VAM and Azospirillum 
brasilense on the growth of barley and pearlmillet have also been reported (Subba 
Rao et ah, 1985). Interactions between A. brasilense and the mycorrhizal fungus, 
Glomus mosseae in relation to their effects on the growth and nutrition of C 3 and C 4 
plants showed that although Azospirillum exhibited C 2 H 4 reduction activity, no 
significant effect of inoculation on N concentration in plant was found. Azospirillum 
and N behaved similarly in enhancing the growth and nutrition of mycorrhizal maize 
plants (Barea et ah, 1983). 

Response of a plant to colonization by mycorrhizae depends on many biotic 
and environmental factors. Plant available P is considered to influence the degree 
of relative growth inhibition or enhancement in mycorrhizal symbiosis (Bethlenfalvay 
et ah, 1982). 

[ 87 ] 



The study of ^zosp/nV/MW-mycorrhiza-host interactions under various P levels 
should allow the Azospirillum or the VAM fungus to be highly competitive for 
photosynthate and hence influence the growth and nutrition of this tripartite 



The response of legumes to inoculation with Rhizobium and mycorrhizae have 
been assessed in various pot and field trials (Subba Rao et al. 1986; Tilak, 1985). 
However, the inoculation with a correct fungal species is as important as the selection 
of Rhizobium species for better growth and development of these plants (Green et al., 
1983). By simultaneous inoculations with Rhizobium sp. and mycorrhiza, legumes 
can receive growth benefits because of improved P and N supplies. The dual 
symbiosis in legumes not only reduce the input of synthetic fertilizers, thereby saving 
energy but also appear to reduce the cost of the system itself in terms of 
photosynthate drain (Kucey and Paul, 1982). 

Distinct responses of lentil to dual symbiosis on a P-deficient soil suggested 
its dependency on Rhizobium and Glomus for N a fixation, N and P nutrition and 
growth (Singh et al., 1984). To derive maximum benefit from dual inoculation with 
Rhizobium and VAM, addition of small amounts of P is also required. Inoculation 
•with Rhizobium and Glomus fasciculatum improved the nodulation, mycorrhizal 
colonization, dry weight, N and P content of Leucaena plants compared to single 
inoculation with either organisms (Manjunath et al., 1984). There is, however, no 
direct interaction between the VAM fungus and the N a fixing bacteria as reported by 
•Carling et al. (1978). They showed that nodulating soybean plants showed increase * 

in total dry weight, nodule dry weight as well as in N 2 -ase and NR activities over y • 

single or non-infected plants. But, when P was substituted for mycorrhizal infection, 
similar growth and enzyme activity increase were observed which suggested the 
.absence of direct interaction between VAM and the N a -fixing bacterium-Rhizobium 
japonicum. 

Rapid colonization by VAM fungus would result in an an enhanced P status, 
'but would lower the level of carbohydrate in the roots. Bradyrhizobium strains 
unable to store P but capable of stroring C and poly-B-hydroxybutyrate could have 
a competitive advantage under these conditions (Pacovsky et al, 1986). 

It, however, appears that dual inoculation with a suitable species of Rhizobium 
and mycorrhizal fungi not only enhances the nutrient content in the above ground 
plant material but also seems to provide a nutrient supply that is well balanced. 
Using labelled ammonium sulphate fertilizer, Subba Rao et al. (1986) reported that 
dual inoculation of Rhizobium sp. and Glomus fasciculatum brought significant increase 
In N a fixation in straw and grain of chickpea over that of the individual organism(s) "W 

jn a sandy-loam alluvial soil. 

Waidyanatha et al. (1979) reported increased N a -ase activity in Pueraria sp. 
•when the growth phosphate response curve became asymptotic and suggested that 



nodule formation may be preferentially stimulated by mycorrhizal infection, which 
make the phosphate directly available to plants. Because there is no contact 
between the mycorrhizal fungi and Rhizobium bacteroids, any P supply must pass 
through the host cells. The role played by the VAM specific phosphatases in the 
arbuscules developed inside root cells adjacent to nodules was suggested as being 
of great importance in phosphate transfer to bacteroids (Asimi et al., 1980). 

VA-mycorrhizal fungi are omnipresent and are being studied extensively 
throughout the globe. In spite of many unanswered questions concerning their use, 
researchers have an obligation, for socio-economic reasons to continue to explore 
means of utilizing these microorganisms. Mycorrhizae and nitrogen-fixers can, 
therefore, be regarded as alternative means for more rational agricultural programmes 
in economising the use of chemical nitrogenous and phosphatic fertilizers. 

REFERENCES 

Asimi, S., Gianinazzi-Pearson, V., Gianinazzi, S 1980. Influence of increasing soil P levels on 

interactions between VAM and Rhizobium in soybeans. Can. J. Bot. 58 : 2200-2205. 
Bagyaraj, D. J., Menge, J. A. 1978. Interaction between a VA-mycorrhiza and A zotobacter and 

their effects on rhizosphere microflora and plant growth. New Phytol. 80 ; 567-573. 
Barea, J. M., Azcon-Aquilar, C. 1982. Interactions between mycorrhizal fungi and soil microorg- 
anisms. In : Les Mycorhizes Biologie et Utilization, National Institute of Agronomic 

Research (INRA), France, pp. 181-193. 
Barea, J. M., Bonis, A. F., Olivares, J. 1983. Interactions between Azospirillum and VA-mycorrhiza 

and their effects on growth and nutrition of maize and rye grass. Soil Biol. Biochem. 

15 : 705-709. 
Bethlenfalvay, G. J., Brown, M. S., Pacovsky, R. S. 1982. Parasitic and mutualistic associations 

between a mycorrhizal fungus and soybean. I. Development of the host plant. Phytopa- 
thology 72 :889-893. 
Brown, M. E , Carr, G. R. 1984. Interactions between Azotobacter chroococcum and VAM and 

their effects on plant growth. /. Appl. Bacteriol. 56 : 429-437. 
Carling, D. E., Brown, M. E., Brown, R. A. 1978. Colonization rates and growth response of 

soybean plants infected with vesicular-arbuscular mycorrhizal fungi. Can. J. Bot. 57 : 

1769-1772. 
Green, N. E., Smith, M. D., Beavis, W. D., Aldon, E. F. 1983. Influence of vesicular-arbuscular 

mycorrhizal fungi on the nodulation and growth of sub-clover. /. Range. Manage. 36 : 

576-578. 
Kucey, R. M. N.. Paul, E. A. 1982. Carbon flow, photosynthesis and N a -fixation in mycorrhizal 

and nodulated faba beans (Viciafaba L.). Soil Biol. Biochem. 14 : 407-412. 
Linderman, R. G. 1988. Mycorrhizal interactions with the rhizosphere microflora : The mycorrhi- 

zosphere effect. Phytopathology 78 : 366-371. 
Manjunath, A., Bagyaraj, D. J., Gopala Gowda, H. S. 1984. Dual inoculation with VA-mycorrhiza 

and Rhizobium is beneficial to Leucaena. PI. Soil 78 : 445-446. 
Mosse, R. 1981. VAM research on tropical agriculture. Res. Bull. Hawaii Instt. Trop. Agri. and 

Human Resources 194 : 14-15. 

[ 89 ] 



Pacovsky, R. S., Fuller, G. 1985. Influence of soil on the interactions between jendomycorrhizae 

and Azospirillum in sorghum. So/7 Biol. Biochem. 17 : 525-535. 
Pacovsky, R. S., Paul, E. A., Bethlenfalvay, G. J. 1986. Response of mycorrhizal and P fertilized 

soybeans to nodulation by Bradyrhizobium and ammonium nitrate. Crop Sci. 26 : 

145-150- 
Singh. O. S., Parasher, V., Bala, S. 1984. Response of lentil to single and combined inoculation of 

Rhizobium and Glomus. In : Symbiotic nitrogen, Ed. B. S. Ghai, USG Publ. Ludhiana, 

India, pp. 159-167. 
Subba Rao, N. S., Tilak, K. V. B R., Singh, C. S. 1985. Effect of combined inoculation of VAM 

and Azospirillum brasilense on pearlmHlet (Pennisetum americanum). PI. Soil 84 : 283-286. 
Subba Rao, N. S., Tilak, K. V. B. R., Singh, C. S. 1986. Dual inoculation with Rhizobium sp. and 

Glomus fasciculatum enhances nodulation, yield and nitrogen fixation in chickpea 

(Cicer arletinum Linn). PI. Soil 95 : 351-359. 
Tilak, K. V. B. R. 1985. Interaction of vesicular-arbuscular mycorrhizae and nitrogen fixers. In : 

Proc. Soil Biol. Symp. Hisar, India, Eds. M. M, Mishra, K. K. Kapoor, pp. 219-226. 
Waidyanatha, U. P., Yoganatham, K, Ariyarathe, W. A. 1979. Mycorrhizal infection on growth 

and nitrogen fixation of Pueraria and Stylosanthes and uptake of phosphorus from two 

rockphosphates. New Phytol. 82 : 147-152. 



[ 90 ] 



Mycorrhiza induced resistance, a mechanism for management of 
crop diseases 

P. VIDHYASEKARAN 

Centre for Plant Protection Studies 

Tamil Nadu Agricultural University, Coimbatore-641 003, India 

Plant Physiologists and Agronomists have exploited the mycorrhizal fungi to 
help plants to acquire mineral nutrients from the soil, especially immobile elements 
such as P, Zn and Cu and also more mobile ions such as S, Ca, K, Fe, Mg, Mn, Cl, 
Br and N. As these fungi alter the nutrition and development of host plants, the 
plants either become more resistant or more susceptible depending upon the host 
and pathogen. In fact better-developed mycorrhizal plant becomes more suscep- 
tible to pathogens than the poorly grown nonmycorrhizal one (Davis et al, 1978). 
Several published reports indicate greater damage of mycorrhizal plants by soilborne 
fungi. In some cases host-parasite relationships lead to less disease incidence on 
mycorrhizal plants mostly because of increased vigour of the plants to tolerate the 
diseases (Graham and Menge, 1982). In such cases high inoculum levels of the 
pathogen decrease the efficacy of mycorrhizal fungi in reducing the disease. 

Mycorrhizae can be exploited in another fascinating way also. Since mycorr- 
hizal fungi also infect the roots, the principle of cross protection with avirulent or 
less virulent isolates can be utilized to manage the soil-borne diseases. The degree 
of success of induced resistance may depend upon the potential of the mycorrhizal 
fungus to induce resistance (Chakravarty and Unestan, 1987). Some of the 
mycorrhizal fungi do not infect the plants when abundant phosphorus is available in 
the soil and such fungi will be of no use in affording cross protection (Graham, 
1988). Prior inoculation with mycorrhizal fungi adapted to infect plants in soils 
fertilized with phosphate-based fertilizers gave effective protection against nematode 
infection in tamarilla (Cooper and Grandison, 1987). Pea root rot caused by 
Aphanomyces enteiches was reduced when the plants were inoculated with Glomus 
fasciculatum two weeks prior to the inoculation of the pathogen. The induced 
resistance was systemic as when root systems were split into two halves, one with 
mycorrhiza and another without the mycorrhiza. The oospore production was 
reduced in both root systems (Rosendahl, 1985). Glomus intrardices controls crown 
and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici in tomato and 
phosphorus nutrition does not have any role in the disease incidence (Caron et al., 
1986). 

[ 91 ] 



Glomus mosseae protected tomato plants against Erwinia carotovora when 
inoculated simultaneously along with the pathogen (Duchesne et ah, 1988). 

For effective management of crop diseases with mycorrhizal fungi, avirulent 
strain of mycorrhizal fungi may have to be selected. The successful mycorrhizal 
fungus which colonizes the roots in a 'susceptibte interaction manner' may not give 
much protection like incompatible interaction. Extensive screening should be taken 
up to identify effective strains to induce resistance. Such a success has been reported 
recently. Two fungi, Glomus mosseae and Gigaspora margarita, neither isolated 
from nor as nutritionally efficient as others on citrus, conferred resistance to 

Phytophthora parasitica in sweet orange. The efficient mycorrhizal fungi like G. 

fasciculatus strains which induced growth of the sweet orange plants did not control 
the disease effectively (Davis and Menge, 1981). 

Most plant cells are capable of elaborating inhibitory substances during their 
quinones, metabolic response to pathogen attack. Phenols, quinones, phytoalexins and 
numerous other compounds have been found in tissues of a variety of plants during 
pathogenesis (Vidhyasekaran, 1988; 1989). Plant cells exposed to symbiotic parasi- 
tism have also been reported to respond by production of substances inhibitory 
to the fungal symbiont (Duchesne et ah, 1987). Accumulation of toxic phenols and 
phytoalexins in mycorrhizal roots has been reported (Krishna and Bagyaraj, 1986; 
Morandi et ah, 1984). The most efficient strains which may increase the synthesis 
of inhibitory substances in the roots should be selected for successful biological 
control of diseases using mycorrhizal fungi. 

REFERENCES 

Caron, M., Fortin, J. A., Richard, C. 1986. Effect of phosphorous concentration and Glomus 
intraradices on Fusarium crown and root rot of tomatoes. Phytopathology 76 : 942-946. 

Chakravarty, P., Unestan, T. 1987. Differential influence of ectomycorrhizae on plant growth and 
disease resistance in Pinus sylvestris seedlings. J. Phytopathology 120 : 104-120. 

Cooper, K. M , Grandison, G. S. 1987. Effects of vesicular-arbuscular mycorrhizal fungi on 
infection of tamarillo (Cyphomandra betacea) by Meloidogyne incognita in fumigated soil. 
Plant Dis.ll : 1101-1106. 

Davis, R. M., Menge, J. A. 1981. Phytophthora parasitica inoculation and intensity of vesicular- 
arbuscular mycorrhizae in citrus. New Phytol. 87 : 705-715. 

Davis, R. M., Menge, J. A., Zentmyer, G. A. 1978. Influence of vesicular-arbuscular mycorrhizae 
on Phytophthora root rot of three crop plants. Phytopathology 68 : 1614-1617. 

Duchesne, L. C, Peterson, R. L., Ellis, B. E. 1987. The accumulation of plant-produced antimicr- 
obial compounds in response to ectomycorrhizal fungi : A review. Phytoprotection 
68 : 17-27. 

Duchesne, L. C, Peterson, R. L., Ellis, R. 1988. Interaction between the ectomycorrhizal fungus 
Pascillus involutus and Pinus resinosa induces resistance to Fusarium oxysporum. Can. J. 
Bot. 66 : 558-562. 

[ 92 ] 



Graham, J. H 1988. Interactions of mycorrhizal fungi with soil-borne plant pathogens and other 

organisms : An introduction. Phytopathology 78 : 365-374. 
Graham, J. H., Menge, J A. 1982. Influence of vesicular-arbuscular mycorrhizae and soil phospho- 
rous on take-all disease of wheat. Phytopathology 72 : 95-98. 
Krishna, K. R., Bagyaraj, D. J. 1986. Phenolics of mycorrhizal and uninfected groundnut var. 

MGS 7. Current Research 15 : 51-52. 
Morandi, D., Bailey, J. A., Gianinazzi-Pearson, V. 1984. Isoflavonoid accumulation in soybean 

roots infected with vesicular-arbuscular mycorrhizal fungi. Physiol. Plant Path. 

24 : 357-364. 
Rosendahl, S. 1985. Interactions between the vesicular-arbuscular mycorrhizal fungus Glomus 

fasciculatum and Aphanotnyces euteiches root rot of peas. Phytopath. Z. 114 : 31-40. 
Vidhyasekaran, P. 1988. Physiology of disease resistance in plants. Vol. I and II. Boca Raton. 

U S. A., CRC Press, pp. 149. 
Vidhyasekaran, P. 1989. Basic research for crop disease management. Vol. I and II. Delhi, Daya 

Publishing House. 



I 93 ] 



Interaction Study of Glomus mosseae and Rhizoctonia solani 

B. R. KHADGE. L. L. ILAG AND T. W. MEW 
International Rice Research Institute, P. O. Box 933, Philippines 

Because of the interaction among microorganisms in soil, the effect of VAM 
fungi on soil-borne plant pathogens is inevitable (Schenek and Kellam, 1978). VA 
mycorrhizae may influence the microbial population of the rhizosphere and vice-versa 
(Menge et ah, 1978). Many authors have reported the interaction between VAM 
fungus and soil-borne plant pathogen. Most of the studies on the biological control 
with VA mycorrhizae do not clarify whether or not it is effect of nutritional mediated 
or direct interaction effect. The split-root method (Menge et ah, 1978) is suitable 
for the study of the interaction between VAM fungus and plant pathogen to diffe- 
rentiate nutritional mediated effect from direct interaction effect. 

In the study, corn (Zea mays L.) var. IPB 1 was used to study the interaction 
between Glomus mosseae and Rhizoctonia solani. 

A reduction in the root growth was observed in R. solani inoculation. 
Rhizoctonia inoculated corn had 29% less root dry weight compared with that of the 
uninoculated check. The plant inoculated with G. mosseae alone gave highest total 
dry root weight. When R. solani was inoculated on the mycorrhizal corn, either on 
the same root portion or separately, there was no significant reduction in root 
weight. 

R. solani multiplied less in the mycorrhizal root than in the nonmycorrhizal 
root. The number of sclerotia recovered form soil with the mycorrhizal root was 
less and viability of sclerotia was reduced significantly. When R. solani was inoculated 
in the mycorrhizal root 35 days after G. mosseae inoculation, there was a reduction 
in root colonization by G. mosseae. The presence of R. solani in the same portion of 
the root significatly reduced the root colonization and chlamydospore production by 
G. mosseae. Besides total root weight reduction in the roots inoculated with 
R. solani was consistently less in the split root portion inoculated with the 
pathogen. The addition of phosphorus in separate root portion did not change the 
multiplication of R. soloni. Thus phosphorus factor only may not be the resistance 
mechanism of the plant inoculated with G. mosseae. There is clear indication of 
direct interaction between the two organisms. The result implies that the effecti- 
veness of G. mosseae may depend on the population of R. solani. High inoculum 

t ■'•'94 ] 



dose may be needed to counteract the pathogen population. On the other hand G. 
mosseae may be useful in the management of Rhizoctonia diseases. 

REFERENCES 

Menge, J. A., Steirle, D., Bagyaraj, D. J., Johnson, E. L. V., Leonard, R. T. 1978. Phosphorus 
concentration in plants responsible for inhibition of mycorrhizal infection. New 
Phytol. *0 -.515. 

Schenck, N. C, Kellam, M. K. 1978. The influence of VAM on disease development. Uni. of 
Florida Agri. Sta. 



[ 95 ] 



Mechanism of resistance of mycoirhizal tomato against 
root-knot nematode 

Y. P. SINGH, R. S. SINGH AND K. SITARAMAIAH 

Department of Plant Pathology, 

G. B. Pant University of Agriculture and Technology, Pantnagar-263 145 (U. P.) 

Vesicular-arbuscuJar (VA) mycorrhizal plants have been shown to react to 
disease differently than non-mycorrhizal plants, however, the mechanisms for 
interaction are poorly understood (Dehne, 1982; Hussey and Roncadori, 1982). 
The antagonistic effects of the fungus on nematode may be either physical or 
physiological in nature. Based on these assumptions, three hypotheses have been 
propounded to understand mechanism of resistance of mycorrhizal plants. These 
include role of mycorrhiza in improving plant vigour and growth to off set yield loss, 
physiological alteration or reduction of root exudates responsible for chemotactic 
attraction of nematode and lastly, direct role of mycorrhiza in retarding the 
development and reproduction of nematode within root tissue. These mechanisms 
may operate singularly or in combination to make mycorrhizal plant resistant 
against invasion of the plant pathogens. 

Attempts were made to determine if VA mycorrhiza, Glomus fasiculatum can 
bring any direct or indirect change in the nature of the Pusa Ruby tomato plants 
which turned it resistant to Meloidogyne javanica. First step towards these investi- 
gations was to know whether difference of attraction for nematodes, if any, existed 
between mycorrhizal and nonmycorrhizal roots or their exudates. Subsequently, 
penetration, development and reproduction of root-knot nematode was studied in 
mycorrhizal and nonmycorrhizal roots. Various biochemical changes including 
lignins, total phenolics, proteins, total sugars and reducing sugars were measured in 
the roots of mycorrhizal as well as nonmycorrhizal plants. 

No correlation was observed between migration of nematodes and their 
penetration of roots, thereby, no direct role of the root exudates of G. fasciculatum 
infected plants in altering the attraction of root-knot nematode for roots could be 
established. 

The nematode penetration was reduced significantly in pre-inoculated 
mycorrhizal roots. Moreover, gall, a manifestation of feeding site of M. javanica, 
developed less on mycorrhizal roots. Also their size was smaller on such roots. The 
smaller size of galls may be the outcome of delayed development of the nematode in 
mycorrhizal plants. 

[ 96 ] 



Reproduction of nematode or recovery of second stage juveniles from soil 
supporting mycorrhiza! plants was significantly less than soil containing nonmycorrhi- 
zal plants. This difference could be justified on the basis of higher counts of females 
without eggs or less number of eggs per egg-sac in mycorrhizal roots. 

Lignins and phenols were found significantly more in the mycorrhizal roots. 
Both the chemicals are known for their role in host resistance (Bhatia et ah, 1972; 
Krishna and Bagyaraj, 1984) especially in influencing the penetration of roots by the 
nematode (Dehne and Schonbeck, 1979). Contrary to it, proteins and sugars were 
less in endophyte inoculated roots. 

The increased resistance of mycorrhizal roots to nematodes can be elicited by 
specific alteration in the physiology of the host plants due to microbial metabolism 
of the endophyte (Dehne, 1982) and its presence in the plant roots. Pre-occupation 
of roots by G. fasciculatum coupled with subsequent biochemical changes appear to 
play a vital role influencing the various events of infection process of M. javanica, 
thereby, making Pusa Ruby tomatoes resistant to root-knot nematode. 
REFERENCES 

Bhatia, I. S., Uppal, D. S., Bajaj, K. L. 1972. Study of phenolic contents of resistant and 

susceptible varieties of tomato (Lycopersicon esculantum) in relation to early blight of 

tomato. Indian Phytopath. 25 : 231-234. 
Dehne, H. W. 1982. Interaction between vesicular-arbuscular mycorrhizal fungi and plant 

pathogens. Phytopathology 72 : 1115-1119. 
Dehne, H. W„ Schonbeck, F. 1979. The influence of endotrophic mycorrhiza on plant diseases : 1. 

Colonization of tomato plants by Fusarium oxysporum f. sp. lycopersici. Phytopath. Z. 

95: 110-116.' 
Hussey, R. S , Roncadori, R. W. 1982. Vesicular-arbuscular mycorrhizae may limit nematode 

activity. PI Dis. 66 : 9-14. 
Krishna, K. R, Bagyaraj, D. J. 1984. Phenols in mycorrhizal roots of Arachis hypogaea. Experientia 

40 : 85-86. 



t 97 ] 



Antagonism of ectomycorrhizal fungi to some common root pathogens 

K. NATARAJAN AND V. GOVINDASAMY 

C. A. S. in Botany, University of Madras, Guindy Campus, Madras-600 025 

A possible beneficial role of ectomycorrhizae in the tree growth and develop- 
ment is that the mycorrhizal fungus protects unsuberized roots from attack by 
parasitic fungi. Zak (1964) postulated that mycorrhizal fungi may conceivably afford 
protection to the root by i) Utilizing root carbohydrates and other chemicals which 
would be attractive to pathogens, ii) Providing a physical barrier to pathogens in the 
form of fungus mantle, iii) Secreting antibiotics which inhibit or kill the pathogens 
and iv) Supporting a protective rhizosphere population of other microorganisms. 

In common with many soil fungi, some mycorrhizal symbionts are capable of 
antibiotic action. Several workers have reported the production of antibacterial and 
antifungal compounds by mycorrhizal fungi in pure culture (Marx, 1971; Pratt, 
1971). 

In the present study the antagonistic effect of some of the ectomycorrhizal 
fungi occuring in Pinus patula and eucalypt plantations in the Nilgiri Hills in 
Southern India against some common root pathogens was studied. Amantia 
muscaria, Laccaria laccata, L. fratema and Suillus brevipes were, tested against six 
root pathogens viz., Armillaria mellea, Cylindrocladium parvum, C. scoparium, Fusarium 
oxysporum, F. solani and Rhizoctonia solani. 

The results indicate that Suillus brevipes inhibited all the fungi tested. It was 
most effective in the case of Fusarium solani and Cylindrocladium parvum and least 
against Rhizoctonia solani. Laccaria laccata inhibited the growth of Armillaria 
mellea, C. parvum, C. scoparium and F. oxysporum. The percentage inhibition was 
high in C. parvum and it was least against C. scoparium. It did not have any effect 
against F. solani and R. &olani. In the case of Amanita muscaria the inhibitory effect 
was found only against R. solani and against all other fungi tested there was no 
inhibitory effect. Laccaria fratema did not have inhibitory effect against any of the 
fungi tested. 

Of the four fungi tested Suillus brevipes inhibited all the root pathogens tested. 
But Marx (1969) demonstrated that Suillus luteus has no effect on Armillaria mellea 
while it inhibited the growth of F. oxysporum and Rhizoctonia spp. He also found 
that Laccaria laccata inhibited half the number of fungi among 48 different pathogens 
tested which include R. solani but no inhibition was noted against A. mellea, C. 

[ 98 ] 



scoparium and F. oxysporum. In the present study the reverse case occurred i.e., 
Laccaria laccata inhibited A. mellea, C. parvum, C. scoparium and F. oxysporum and 
showed no inhibition on F. solani and R. solani. But other studies have shown that 
Laccaria laccata to be highly antagonistic to F. oxysporum in natural conditions 
(Sinclair et al, 1982; Sylvia and Sinclair, 1983). 

Hyppel (1968) has shown that Amanita muscaria produced antifungal 
compounds which inhibited the growth of pathogens but in the present study A. 
muscaria weakly inhibited only R. solani among the six test pathogens. L. fraterna 
showed no inhibition against any of these pathogens. 

Results of antagonism test between mycorrhizal fungi and root pathogens 
conducted on nutrient agar medium can only be regarded as suggestive relative to 
natural conditions. There is further scope to assess to value of these pine mycorrhi- 
zal isolates against the various root pathogens in the nursery trials. 
REFERENCES 

Hyppel, A. 1968. Antagonistic effects of some soil fungi on Forties annosus in laboratory experi- 
ments. Stud. Forest. Suec. 64 : 18. 

Marx, D. H. 1969. The influence of ectotrophic mycorrhizal fungi on the resistance of pine roots 
to pathogenic infections. I. Antagonism of mycorrhizal fungi to root pathogenic fungi 
and soil bacteria. Phytopathology 59 : 158-163. 

Marx, D. H. 1971. Ectomycorrhizae as biological deterrents to pathogenic root infections. In: 
"Mycorrhizae", Ed. E. Hacskaylo, USDA Misc. Publ. No. 1189, US Govt. Printing 
Office, Washington, D. C, pp. 81-96 

Pratt, B. H. 1971. Isolation of basidiomycetes from Australian eucalypt forest and , assessment of 
their antagonism to Phytophthora cinnamomi. Trans. Brit. Mycol. Soc. 56 : 243-250. 

Sinclair, W. A., Sylvia, D. M., Larsen, A. O. 1982. Disease suppression and growth promotion in 
Douglass-fir (Pseudotsuga menziesii) seedlings by the ectomycorrhizal fungus Laccaria 
laccata. For. Sci. 28 : 199-201. 

Sylvia, D. M., Sinclair, W. A. 1983. Phenolic compounds and resistance to fungal pathogens 
induced in primary roots of Douglas-fir (Pseudotsuga menziesii) seedlings by the ectomyco- 
rrhizal fungus Laccaria laccata. Phytopathology 73 : 390-397. 

Zak, B. 1964. The role of mycorrhizae in root disease. Ann. Rev Phytopathol. 2 : 377-392. 



[ 99 ] 



Influence of VA mycorrhizal colonization on root -knot nematode 
infestation in Piper nigrum L. 

P. SIVAPRASAD, ARTHUR JACOB, S. K. NAIR AND BABU GEORGE, 

Kerala Agricultural University, College of Agriculture, 

Vellayani, Trivandrum-695 522 

The role cf vesicular-arbuscular mycorrhizae (VAM) in reducing the harmful 
effect of root infestation by many parasitic nematodes in crop plants is now well 
recognized (Hussey and Rancadori, 1982). In the present investigation the specific 
effect of inoculation of pepper {Piper nigrum L.) vines with VA mycorrhizae in the 
presence of root-knot nematode, Meloidogyne incognita was studied. 

The cuttings of pepper cultivar Panniyur 1 were raised in pots filled with 10 kg 
of M. incognita free red sandy loam soil (pH 5.2, 4.0 mg k^ -1 available P) preino- 
culated with cultures of VAM (sand : soil mixture containing 320 spores) wherever 
necessary. Nematode inoculation was done artificially with second stage infective 
larvae of M. incognita (1 g -1 soil) on 90th day of plant growth. There were six 
treatments, viz., control, inoculated with Glomus fasciculatum alone, G. etunicatum 
alone, M. incognita alone, G. fasciculatum along with M. incognita and G. etunicatum 
along with M. incognita. Experiment was conducted in CRD with four replications 
each. Observations were recorded on root-knot index, nematode population in root 
and soil, mycorrhizal colonization (Phillips and Hayman, 1970), plant height and 
shoot and root dry weights on 18th day of plant growth. 

There was significant reduction in root-knot index in plants preinoculated 
with either culture of VAM. The reduction in root-knot index was to the extent of 
32.4% with G. fasciculatum and 36% with G. etunicatum. This indicated that preino- 
culation of pepper vines with VA mycorrhiza will be highly useful in reducing the 
degree of root infestation by M. incognita. One of the possible mechanisms of VAM 
interaction with nematode is that when both are present at the same time in the soil, 
it will induce certain degree of competition between them for root colonization in 
which often the mycorrhizal association of beneficial nature is preferred by the host 
plant (Sikora and Scho'nbeck, 1975). Further, it will be possible for the VAM to 
establish well earlier in the root system becauce of the preinoculation and rapid rate 
of root colonization. This may result in the alteration of root physiology of host 
plant (Sikora, 1978) by way of increasing wall thickness and changing the chemical 
composition of root and root exudates. Thus this sort of preferential and earlier 
root colonization by VAM in pepper will lead to a type of host restriction for sub- 

[ 100 ] 



sequent root infestation by M. incognita. It was further observed that even the root 
and soil population of this nematode is considerably reduced when plants are 
mycorrhizal. This reduction in population was to the order of 53.3 and 47.5% with 
G. fasciculatum and 40 and 34.2% with G. etunicatum inoculation in root and soil 
respectively. 

The above beneficial effect of VAM had a favourable effect on plant growth 
as well. The extent of mycorrhizal association was significantly high in inoculated 
plants. Presence of M. incognita did not affect the mycorrhizal colonization. 

Proper VA mycorrhizal association in crop plants has already been reported 
to induce better plant growth (Mosse and Hayman, 1971). This was evident from 
the improved growth parameters observed in pepper under inoculation with VAM. 
The plant height of 122 and 113 cm, shoot and root dry weight of 12.1 and 11.6 g 
and 1.3 and 1.5 g were recorded for G . fasciculatum and G. etunicatum respectively, 
which was significantly higher than the control. However, more interesting was the 
better growth of pepper vines inoculated with VAM even in the presence of the root- 
knot nematode, M. incognita. The increase in root dry weight due to > G. fasciculatum 
(77.1%) and G. etunicatum (54.2%) and shoot dry weight due to G. etunicatum 
( 67 -4%), were significantly high when compared to plants inoculated with M. incognita 
alone. 

Thus the present investigation clearly showed that it will be highly beneficial 
to have mycorrhizal pepper cuttings for field cultivation especially in areas where 
root-knot nematode is an endemic problem. 

REFERENCES 

Hussey, R. S., Rancadori, R. W. 1982. Vesicular-arbuscular mycorrhiza may limit nematode 

activity and improve plant growth. Plant Dis. 66 : 9-14. 
Mosse, B., Hayman, D. S. 1971. Plant growth responses to vesicular-arbuscular mycorrhiza. II. 

In unsterilized field soil. New Phytol 70 : 29-34. 
Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing and staining parasitic and 

vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Brit. 

Mycol. Soc. 55 : 158-161. 
Sikora, R. A., Scho'nbeck, F. 1975. Effect of vesicular-arbuscular mycorrhiza (Endogone mosseae) 

on the population dynamics of the root-knot nematodes Meloidogyne incognita and M. 

hapla, VIII. International Plant Protection Congress, Moscow, pp. 158-164. 
Sikora, R. A. 1978. Einfluss der endotrophen mycorrhiza (Glomus mosseae) auf das wirt-Parasit- 

verhaltnis von Meloidogyne incognita in tomaten. Z. Pflanzenkrankh Pflanzen Schutz. 

85 : 197-202. 



[ 101 ] 



The role of VA mycorrhiza in controlling certain root diseases of 
tobacco 

D. V. SUBHASHINI 
Central Tabacco Research Institute, Rajahmundry 

Studies on the interaction between root-knot nematode and mycorrhiza! 
fungus Glomus fasciculatum alone showed highest gall index whereas plants treated 
with both mycorrhizal fungus and nematode showed moderate gall index of 3 and 
control recorded the gall index of 4. 

Interaction between mycorrhizal fungus G. fasciculatum and Orobanche with 
treatments : control, mycorrhiza alone, Orobanche alone and mycorrhiza plus 
Orobanche revealed that the plants treated with both mycorrhiza and Orobanche also 
showed the emergence of Orobanche shoots and their growth is almost equal to that of 
plants treated with Orobanche alone. Similar study has been conducted in Orobanche 
sick soil and CTRI farm with 4 mycorrhizal cultures viz. G. fasciculatum, G. constric- 
tum, G. mosseae and Acaulospora along with the control. Emergence of Orobanche 
was observed in all the 4 cultures snowing high intensity of infection as that of 
control. 

Studies on the interaction between Pythium and mycorrhiza in tobacco 
nurseries revealed that non-mycorrhizal plots were wiped off by Pythium attack 
whereas mycorrhizal plots after inoculation of Pythium also continued to produce 
healthy, transplantable seedlings out of 4 cultures of mycorrhiza, G. fasciculatum, G. 
constrictum, G. mosseae and Acaulospora tested for Pythium resistance, of these 
G. fasciculatum was found to be promising. 



t 102 ] 



Prevalence of native VAM fungi and their relative performance in 
infectivity of local crops 

C. NARAYANA REDDY AND RAJENDRA SINGH BA1S 
Dept. of Botany, Gulbarga University, Gulbarga-585 106 

Use of VAM fungi for the improvement of crop productivity requires selection 
of an efficient and appropriate fungus (Menge, 1983), the right type of soil and the 
identification of crop (Krikun et al., 1987). An effective mycorrhizal association is 
required for every crop for P uptake in nearly all soils. Two of the criteria suggested 
for appropriateness are infectivity and efficacy (Haas and Krikun, 1985) besides, the 
root colonization ability and the ability of the fungus to survive in soil. The plant 
growth response usually is dependent upon the quantity of VAM formed ea r ly in the 
growth season of rop. Since, different VAM fungi differ in their ability to form 
efficient VAM with different crop plants and sometimes indigenous endophytes 
were less efficient than introduced (Manjunath and Bagyaraj, 1980). Studies were 
undertaken (a) to isolate native VAM and (b) to study their relative performance 
on local crops. 

The VAM spores were recovered from local soil samples of Gulbarga by 
wetsieving and and decanting method (Gerdemann and Nicolson, 1963). Different 
spore types recognized were purified and multiplied by raising single spore cultures. 
The spores thus isolated were identified. 

Four local crops, chickpea (cv. Annigeri), pigeonpea (GSI), sorghum 
(cv. Neerjola) and onion (cv. Desi) were raised in pots containing infested loamy sand 
soil (spore concentration 45±5/gm soil) with five VAM fungi (3 native +2 
introduced) seperately examined after 35 days, for % root colonization (Giovanetti 
and Mosse, 1980) after clearing and staining (Phillips and Hayman, 1970). 

Three VAM fungal species, all belonging to the genus Glomus viz. G. cons- 
trictum, G. fasciculatum and G. pggregatum were recorded in the present survey of 
native soils. All the four local crops responded to infectivity by all five VAM fungi 
tested with characteristic vesicles and arbuscles, G. aggregatum, though infected 
sufficiently, the formation of vesicles and arbuscles were scarcely seen. The % root 
colonization differed with all VAM fungi tested with respect to different crops tested 
confirming the earlier findings (Manjunath and Bagyaraj, 1980). High mycorrhizal 
root infection was recorded in all the crops except sorghum in soil infested with 
G. fasciculatum irrespective of the source followed by G. aggregatum. The response 

[ 103 ] 



of the crops to mycorrhization with G. constriction and Gigaspora margarita was 
considerably less irrespective of the crop and did not show any appreciable degree of 
infection in the early development. Many legumes are poor forgers for soil P and in 
the present study both pjgeonpea and chickpea showed significantly higher VAM 
formation than onion and sorghum crops showing their higher dependency on VAM 
associations as evidenced already in pigeonpea which responded less to P fertilizer 
application than sorghum. Since the plant growth response usually is dependent 
upon the quantity of VAM formed early in the growth season and the efficiency of 
VAM symbiosis is the sum of interaction between, the fungal endophyte, the host 
and the soil (Hayman, 1983), the present study helps for an early detection and 
selection of VAM inoculant which is compatible with local soils. 

In the present survey of soils of Gulbarga for native VAM fungi 3 species viz. 
Glomus fasciculatum, G. aggregatum, G. constriction were recorded and tested on 4 
local crops along with two other VAM fungi G. fasciculatum and Gigaspora margarita 
(introduced) by pot culture experiments using local soil. Variability was ovserved 
in infectivity and % mycorrhization in all the crops. G. fasciculatum (irrespective of 
the source) proved better inoculant on all the crops as its % root colonization was 
significantly higher when compared to the rest. G. aggregatum was the next best 
while the other did not show any appreciable degree of infection. 

REFERENCES 

Gerdemann, J. W., Nicolson, T. H., 1963. Trans. Brit. Mycol. Soc. 46 : 235-244. 

Giovanetti, M., Mosse, B. 1980. New Phytol. 84 : 489-495. 

Haas, J. H , Krikun, J. 1985. New Phytol. 100 : 613-621. 

Hayman, D. S. 1983. Can. J. Bot. 61 : 944-963. 

Krikun, J., Haas, J. H., Bar-Yosef, B. 1987. Angew. Botanik. 61 : 97-105. 

Manjunath, A., Bagyaraj, D. J. 1980. Curr. Sci. 51 : 707-708. 

Menge, J. A. 1983. Can. J. Bot. 61 : 1015-1024. 

Phillips, J. M, Hayman, D. S. 1970. Trans. Btit. Mycol. Soc. 55 : 158-161. 



[ 104 ] 



Role of VA mycorrhizae, phosphate solubilising bacteria and their 
interactions on growth and uptake of nutrients by wheat crop 

A. C Gaur and J. P. S. Rana 

Division of Microbiology 

Indian Agricultural Research Institute 

New Delhi-12 

Role of phosphate solubilising bacteria, VA mycorrhizae and their interactions 
on growth, yields and uptake of nutrients by Triticum aestivum was studied in sandy 
loam alluvial soil in pot culture condition without and with application of chemical 
nitrogen at 60 kg and 80 kg N ha -1 as urea and phosphorus and 60 kg P a O s as 
mussoorie rock phosphate ha -1 . Phosphate solubilising bacteria such as Pseudomonas 
striata and Agrobacterium radiobacter and VA mycorrhizae (Glomus fasciculatum and 
Gigaspora margarita) were used. Wheat seeds were inoculated with either of PSB 
and soil was inoculated with either of VA mycorrhizae singly and in combinations. 
Each treatment was replicated 9 times, 3 pots each were kept to study dry matter and 
grain and straw yields and 6 pots were kept for the rhizosphere study of PSB, 
nutrient uptake and dry matter yields. 

The results showed that inoculation with phosphate solubilising bacteria and 
VA mycorrhizae improved dry matter yield at various growth periods. The use of 
nitrogenous and phosphatic fertilizers augmented the dry matter yields significantly 
over the control and microbial inoculation treatments. Pseudomonas striata and 
Glomus fasciculatum when used together were found more effective than either of 
them but the treatment, P. striata and G. fasciculatum with chemical fertilizers (N a -, 
and P 80 ) gave the highest yield which was significant to all the treatments. Similarly 
Agrobacterium radiobacter with either G. fasciculatum or Gigaspora margarita and soil 
amended with chemical fertilizers also gave significant increases. 

Grain yield was significantly augmented with simple inculation of P. striata 
alone. The other microbial treatments were at par with the control. The application 
of N 120 P 8 o gave the highest yield which was significantly superior to all microbial 
inoculants used singly except P. striata which was at par with this treatment. The 
combinations of either P. striata was at par with this treatment. Likewise A. 
radiobacter and G. fasciculatum/Gigaspora margarita gave increased yields over single 
inoculations. Phosphorus uptake was maximum with P striata alone, chemical 

r [ 105 ] 



nitrogenous and phosphatic fertilizers and combined inoculation ofP. striata -f G. 
fascictdatwn/Gigaspora margarita. The effect of A. radiobacter and VAM combina- 
tions were less marked but the results were statistically at par. The rhizosphere 
counts of PSB and percent infection by VAM showed that the inoculation of PSB 
help in their establishment in the soil. Single inoculation gave their higher numbers 
in the rhizosphere of the plant. The establishment of A. radiobacter was less marked 
ar compared to P. striata. The percent root infection by VAM was enhanced due 
to its inoculation of soil. 



[106 ] 



Interaction of vesicular-arbuscular mycorrhiza (Glomus etunicatum 
and Rhizobium in cowpea 

B. RAMARAJ AND N SHARMUGAM 
Tamil Nadu Agricultural University, Coimbatore-641003 

The beneficial effect of vesicular-arbuscular mycorrhizae on host plants is well 
known (Jalali and Thareja, 1982). Hayman and Mosse (19i?9) reported the effect of 
VA mycorrhiza on legumes. But studies on the interaction of VA mycorrhiza and 
Rhizobium are very few. Since 'P' is essential for biological nitrogen fixation and VA 
mycorrhiza helps to increase the uptake of 'P', the present study was taken up to 
investigate the interaction effect of Glomus etunicatum and Rhizobium in cowpea 
(Vigna unguiculata) . The effects of G. etunicatum alone and along with Rhizobium 
besides Rhizobium alone were studied. 

Both shoot and root weights were on par in G. etunicatum inoculated plants, 
G. etunicatum+ Rhizobium inoculated plants and Rhizobium inoculated plants in 
sterilized soil. But these treatments were significantly superior to untreated plants. 
The grain yield also was on par in the VAM inoculated plants, Rhizobium inoculated 
plants and in plants with dual inoculation of V AM+ Rhizobium. But they were all 
significantly superior than plants without any treatment. The nodule number was 
significantly more in the dual inoculation of VAM + Rhizobium than either with VAM 
alone or Rhizobium alone which were in turn bstter than uninoculated plants. The 
percent colonization with VAM was similar in VAM inoculation alone and in dual 
inoeulation of VAM and Rhizobium. 

In unsterilized soil, the shoot weight and grain yield were on par in the plants 
inoculated with VAM, Rhizobium and dual inoculation. But they were significantly 
superior to uninoculated plants. The root weight in the plants with dual inoculation 
was significantly better than other treatments. The nodule number was significantly 
more in plants with dual inoculation of VAM and Rhizobium than either VAM or 
Rhizobium alone. 

In both sterilized and unsterilized soil conditions, dual inoculation with VA 
mycorrhiza and Rhizobium increased the rhizobial nodules and mycorrhizal coloniza- 
tion and consequantly the biomass than either of them alone. The increase in 
nodulation may be due to the enhancement of «P' uptake by VAM. Similar obser- 
vations were made by Smith and Daft (1977) and Islam et al. (1980). 

[ 107 ] 



REFERENCES 

Hayman, D. S., Mosse, B. 1979. Improved growth of white clover in hill grass land* by 

mycorrhizal inoculum. Ann. Appl. Biol. 93 : 141-148. 
Islam, R., Ayanaba, A., Sanders, F. E. 1980. Response of cowpea (Vlgna uuguiculata) to 

inoculation with VA mycorrhizal fungi and to rock phosphate fertilization in some 

unsterilized Nigerian soils. Plant Soil 54 : 107-117. 
Jalali, B. L., Thareja, M. L. 1982. Studies on the plant growth responses to vesicular-arbuscular 

mycorrhiza. Ann. Prog. Rept. I. C. A. R. scheme on studies on plant growth responses 

to vesicnlar-arbuscular mycorrhiza, Haryana Agric. Univ. Hisar. 
Smith, S. E., Daft, M. J. 1977. Interactions between growth, phosphate content and nitrogen 

fixation in mycorrhizal and non mycorrhizal Medicago saliva. Aust. J. PI. Physiol. 

4 : 403-413. 



Interaction between Glomus versiforme and Azospirillum brasilense 
in barley 

MAHIMA NEGI AND K. V. B. R. TILAK 

Division of Microbiology, 

Indian Agricultural Research Institute, Dew Delhi-110012 

Vesicular-arbuscular mycorrhizal (VAM) associations are formed with a large 
number of graminaceous plants. Recent researches have also established that some 
of these plant species which are able to form VAM are also mutualistically associated 
with nitrogen-fixing procaryotes. Nitrogen fixing bacteria, particularly of genus 
Azospirillum are able to associate closely with the roots of gramineae and increase 
crop production (Neyra and Dobereiner, 1977). Improvement in yield due to 
inoculation with VAM and Azospirillum on barley and pearlmillet has also been 
reported (Subba Rao et al., 1977). The present study deals with the aspects of plant 
improvement in terms of nutrient (nitrogen and phosphorus) uptake and nitrogen 
fixation in barley in the presence of VAM fungus, Glomus versiforme and N a -fixing 
Azospirrillum brasilense under varying levels of nitrogen and phosphorus. 

A pot culture experiment was conducted with sandy-loam soil which was 
deficient at available phosphorus (4, 5 kg ha -1 ) using barley (Hordeum vulgare L.) 
var. 62-65-7-4-36 as host plant. A mixed culture of the most efficient strains of 
Azospirillum brasilense (B-l and B-2) was used. Soil and sand mixture containing 
extramatrical chlamydospores and root segments of Cenchrus ciliaris infected with 
Glomus versiforme (Daniels and Trappe) grown for 90 days which contained 250-300 
spores per 100 g soil served as inoculum. Nitrogen was applied as labelled ammo- 
nium sulphate with 5% 15 N atom excess at the rate of 50 kg N ha- 1 . While 
phosphorus was applied as single superphosphate at the rate of 30 kg P a 6 ha- 1 . 
The plants were harvested at different stages of plant growth and were subjected to 
N and P analysis following standard methods (Jackson, 1967). The atom percent 
15 N in plant samples was determined by an emission spectrophotometer and the N 
fixed by Azospirillum per plant was calculated as under : 

N fixed by Azospirillum/plant = 

(Soii and atmospheric N uptake by inoculated plant)— (Soil and atmospheric N 

uptake by uninoculated plant) 

In shoots in the presence of combined inoculation and N and P application, 
the phosphorus uptake, as high as 39.9 mg/plant was recorded. Inoculation with 

C 109 ] 



mycorrhiza alone had no significant effect on P uptake by roots as well as by shoots. 
In grains also dual inoculation resulted in maximum uptake (120.2 mg plant -1 ) in 
the presence of both N and P application. The higher uptake in plants in the 
presence of both N and P due to combined inoculation highlights the importance of 
VAM in conjunction with Azospirillum. the presence of Azospirillum may possibly 
increase N mineralisation in soil (Pacovski and Fuller, 1985). Better translocation 
rates of phosphorus within and transfer out of the hyphae in the presence of both the 
endophytes resulted in increased P uptake in roots and shoots. 

Plant inoculated with both VAM and Azospirillum resulted in more nitrogen 
fixation than that in singly inoculated ones. A maximum of 335.3mg N fixed plant -1 
at 120 days in dually inoculated NjP treatment. In case of grains, however, a 
maximum of 575.4 mg N was fixed per plant in NjPj treatment as against 315.4 mg 
N fixed NjPo treatment in plants inoculated with mycorrhiza alone. The observed 
effect has been attributed to a summation of seperate mycorrhizal and Azospirilluu 
effects. The effect was, however, more pronounced in the presence of phosphorus 
supporting the fact that phosphorus is ruquired for nitrogen fixation. The phospho- 
rus male available by the VA-mycorrhizal fungus might have contributed towards 
enhanced N a -fixation by Azospirillum. 

REFERENCES 
Jackson, M. L. 1967. Soil chemical Analysis. Prentice Hall of India. Publ. New Delhi, India. 
Neyra, C. A., Dobereiner, J. 1977. Nitrogen fixation in grasses. Adv. Agron. 29 : 1-38. 
Pacovski, H. S., Fuller, G. 1985. Influence of soil on the interactions between endomycorrhizae 

and Azospirillum in sorghum. Soil Biol. Biochem. 17 : 525-535. 
Subba Rao, N. S., Tilak. K. V. B. R., Singh, C. S. 1985. Effect of combined inoculation of 

VAM and Azospirillum brasilense on pearl millet (Pennisetum americanum). PI. Soil. 

84 ! 283-286. 



[ no ] 



Vesicular arbuscular mycon hizal associations and root colonization 
in some important tree species 

H. S. THAPAR AND A. K. VUAYAN 
Forest Research Institute, Dehra Dun-248 006 

Many commercially important hardwood forest trees are naturally infected 
with vesicular-arbuscular endophytes. However, little work has been done to improve 
seedling quality in forest tree nurseries by manipulation of these fungi and under- 
stand, levels of root colonization before transplanting. Adequate root colonization 
by VAM fungi in natural and artificially inoculated soils is of paramount importance 
in improving seedling vigour and it proves a useful index to predict the performance 
of seedlings in artificial regeneration programmes in different stresses and agricul- 
turally unproductive sites. Seedling development of hardwood species that normally 
form VAM has not been satisfactory in forest nurseries and consequently seedling 
quality remains a major problem in artificial establishment of hardwood plantations 
of sweet gum (Liquidamber styraciflua) in United States (Kormanik et ah, 1982). 
Keeping in view the importance of root colonization by VAM, the present study was 
undertaken to evaluate the frequency and level of cortical infection in nursery seed- 
lings belonging to 19 genera and 14 families of angiosperms. 

A quantitative evaluation of the intensity of VA mycorrhizal infetion in nursery 
seedlings of 20 important hardwood tree spp. belonging to 19 genera of 14 families 
was conducted in nurseries at New Forest, Dehra Dun. 

The frequency of VAM infection and percentage of infection in roots among 
species within a family and among different host genera were found to be variable. 
Highest level of root colonization (92%) was recorded in Michelia champaca -and 
Toona ciliata whereas very low (I to 6%) levels were recorded in Albizia lebbek, 
Grewia robusta and Madhuce longifolia. The percentage infection was almost same 
in Terminal ia arjuna, Dendrocalamus st rictus, Dalbergia sissoo, Acacia auriculiformis, 
Emblica officinalis, Oka glandulifera, Acacia nilotica and Serraca asoca (<40%). 
Species of Glomus macrocarpus and Sclerocystis coremioides were found in the 
rhizosphere of infected roots. Heavy arbuscular infection was found in Madhuca 
longifolia, extramatrical spores in Acacia auriculiformis and heavy vesicular infection 
in Acacia auriculiformis, Dalbergia sissoo and Delonix regia. The highest frequency 

[ JU ] 



of VAM infection was recorded in Toona ciliata (83.8%), followed by Michelia 
champaca (79.54%), Jackranda minosifolia (67.25%) and Dendrocalamus strictus 
(65. 5%) while it was lowest in Albizia lebbeck (8.33%). Low frequency levels of 
VAM infection in nursery seedling are indicative of the need of inoculation of nursery 
stocks with efficient VAM endophytes for better nursery and field performance. 

REFERENCE 

Kormanik, P. P., Schultz, R. C. Bryan, W. C. 1982. The influence of vesicular-arbuscular 
mycorrhizae on the growth and development of light, hardwood tree species. Forest Sci. 
28 : 531-539. 



1 112 J 



Interaction between Glomus fasciculatum and two phosphate 
solubilizing fungi in finger millet 

M. N. GOPALAKRISHNA, D. J. BAGYARAJ AND M. VASANTHAKRISHNA 

Department of Agricultural Microbiology, University of Agricultural Sciences, 

GKVK, Bangalore-560065 

Research in the last three decades has established that plants inoculated .with 
vesicular-arbuscular (VA) mycorrhizal fungi grow better through increased uptake of 
phosphorous and other mineral nutrients especially in soils of low fertility (Jeffries, 
1987). Gain in plant dry matter has been demonstrated with increase in phosphorous 
availability caused by the P-solubilizing bacteria inoculated to soil (Gaur and Ostwal, 
1972). Synergistic interactions between VA mycorrhizal fungi and P-solubilizing 
bacteria with consequential improvement in plant growth has been reported earlier 
(Raj et al. 1981). The objective of the present study is to examine the interaction 
between two phosphate solubilizing fungi Penicillium funiculosum and Aspergillus niger, 
and the VA mycorrhizal fungus, Glomus fasiculatum in the rhizosphere and its effect 
on growth and mineral content of finger millet. After 50 days of transplanting, plant 
and soil samples were collected for various analyses. 

Dual inoculation with G. fasciculatum and P. funiculosum recorded the highest 
mycorrhizal spore count in soil. But there was not much difference in per cent root 
colonization between mycorrhiza inoculated plants with and without phosphate 
solubilizing fungi. However, G. fasciculatum plus P. funiculosum treatment exhibited 
slightly more root colonization. The populations of introduced phosphate solubilzing 
fungi multiplied and remained in significantly higher numbers in the rhizosphere for 
a longer period. 

Plants inoculated with both mycorrhiza and phosphate solubilizing fungi took 
up more P and K and grew better. Treatment with G. fasciculatum plus A. niger 
recorded the highest Zn concentration. Dual inoculation failed to increase Mn 
uptake. 

Dual inoculation with Glomus fasciculatum and P-solubilizing fungi Penicillium 
funiculosum or Aspergillus niger had synergistic interaction with each other with 
consequential improvement on growth and nutrient uptake of finger millet, 

[ H3] 



REFERENCES 

Gaur, A. C, Ostwal, K. P. 1972. Influence of phosphate dissolving bacilli on yield and phosphate 

uptake by wheat crop. Ind. J. Exp. Biol. 10 : 393-394. 
Jeffries, P. 1987. Use of mycorrhizae in agriculture. Crit. Rev. Biotech. 5 : 319-357. 
Raj, J., Bagyaraj, D. J., Manjunath, A. 1981. Influence of soil inoculation with vesicular- 

arbuscular mycorrhiza and a pnosphate-dissolving bacterium on plant growth and 3-p 

uptake. 50/7 Biol. Biochem. 13 : 105-108. 



[114 ] 



Infection by a fungal endophyte, Balansia sclerotica enhances 
vesicular-arbuscular mycorrhizal (VAM) association in lemongrass 

K. K. JANARDHANAN, ABSAR AHMAD AND M.L. GUPTA 

Central Institute of Medicinal and Aromatic Plants, Post Bag No. 1 

P. O. RSM Nagar, Lucknow-226016 

Lemongrass (Cymbopogon flexuosus (Steud.) Watts) is an important essential 
oil bearing plant commercially cultivated in India. The plant is the source of the 
essential oil, lemongrass oil, the main constituent of which is citral (75-85%). Citral 
is a basic raw material for the synthesis of (3-ionones, a precursor for the synthesis of 
a number of aromatic compounds and vitamin A. Citral is also used extensively in 
perfumery, soap and cosmetic industry (Anonymous, 1950). A variety of lemongrass 
(Kerala local) introduced for experimental cultivation was found to produce abnormal 
and deformed inflorescences. The malformations resulted in grassy-shoot or phyllody 
appearance. Observations revealed that these plants were infected with Balansia 
sclerotica (Pat.) Hohnel (Janardhanan et ah, 1989). The disease is systemic. 
Balansia sclerotica infected plants produced significantly higher tillering and biomass 
than the healthy plants. 

Vesicular-arbuscular mycorrhizae (VAM) impart significant beneficial effect 
to plant growth (Mosse, 1973). These symbiotic associations are therefore, impor- 
tant in crop and biomass production. 

An attempt was made to find out the effect of B. sclerotica infection on the 
VAM-association in lemongrass. Healthy and B. sclerotica infected plants were 
examined for VAM-association. Both infected and healthy plants were found to be 
associated with three Glomus species. Level, of VAM infection in B. sclerotica 
infected roots was 89.6%, while it was 44.6% in healthy plants. Rhizosphere soil 
of B. sclerotica infected plants showed greater VAM spore population (1211/100 g 
soil) than healthy plants (549/100 g soil). Hence, VAM-association was significantly 
higher in plants infected with the fungal endophyte, B. sclerotica. The examination 
of roots and the rhizosphere soils of healthy and B. sclerotica infected plants supports 
this conclusion. 

The results of the investigation indicate that endophytic infection of B. 
sclerotica had significant influence on the VAM-association. Enhanced VAM- 
association can be one of the contributing factors for better growth performances and 
biomass production of endophyte infected grasses. It is now recognised that one of 

[ 115 ] 



the benefits of VAM-association might be the reduction in disease expression due to 
pathogenic microorganisms (Schenck, 1981). The present finding, however, is 
contradictory to this concept. The VAM-association appears to support the growth 
of endophyte infected grasses. This is the first attempt to study the impact of a fungal 
endophyte on VAM-association in plants. 

REFERENCES 

Anonymous, 1950. The Wealth of India, Raw Materials, Vol. 2. Council of Scientific and 

Industrial Research, New Delhi, pp. 414-416. 
Janardhanan, K. K„ Ahmad, A., Gupta, M. L„ Husain, A. 1989. Grassy-shoot, a new disease 

of lemongrass caused by Balansia sclerotica. J. Phytopathology (in press) 
Mosse, B. 1973. Advances in the study of vesicular-arbuscular mycorrhiza. Ann. Rev. 

Phytopath. 11 : 171-196. 
Schenck, N. C. 1981. Can mycorrhizae control root disease? Plant Dis. 65 : 2?0-34. 



[ H6 ] 



Endophytic mycorrhiza in different varieties of Litchi chinensis Sonn. 
and its effect on rhizosphere-microbial population 

S. PANDEY AND V. K. SINGH 

Deptt. of Microbiology, Faculty of Basic Sciences and Humanities, Rajendra Agricultural 

University, Bihar Pusa (Samastipur)-848125, India 

The species of Rhizophagus belonging to the vesicular-arbuscular group of 
phycomycetous endophytes have been observed to be in association with the roots 
of different varieties of Litchi chinensis Sonn. Rhizosphere of Kasva, Deshi and 
Purbi varieties of mycorrhizal litchi had higher population of bacteria than the other 
varieties studied. The protozoal population were also higher in these varieties as well 
as in the late Bedana variety. There was also a marked difference in the frequencies 
of Gram negative and Gram positive bacteria in the non-rhizosphere soil as compared 
to mycorrhizal rhizosphere of different litchi varieties. However, there was a clear 
difference in the bacterial population in the rhizosphere of different litchi varieties. 
Results indicated that the rhizosphere population types differ not only with non- 
rhizosphere soils, but also with mycorrhizal formation in different varieties of litchi, 
though the differences in the later case were not marked. 



t H7 ] 



Interaction of VA mycorrhizal fungus and Tylenchulus semipenetrans 
on citrus 

P. P. S. BAGHEL, D. S. BHATJI AND B. L. JALALI 
Haryana Agricultural University, Hisar-125004 

The growth of citrus is greatly influenced by vesicular arbuscular mycorrhizal 
(VAM) fungi (Nemec, 1978). Tylenchulus semipenetrans is known for causing slow 
decline, or die back disease in this major fruit crop. The concomitant incidence of 
nematode and VAM fungi influences the host growth as a result of varying interac- 
tion, antagonistic or beneficial to each other (Fox and Spasoff, 1972). Presence of 
both the organisms, VAM fungus (Baghel, 1985) and T. semipenetrans (Baghel et al., 
1980) in Haryana, on commonly grown citrus root stock 'Jatti Khatti' (Citrus 
jambhiri) created interest in their interaction studies. The present investigation was 
carried out to observe the individual and combined effect of VAM fungus Glomus 
mosseae and Tylenchulus semipenetrans on the growth of citrus root stock {Citrus 
jambhiri) seedling and their effect on development of each other. 

Surface sterilized seeds of 'Jatti Khatti' (C. jambhiri) were sown in earthen 
pots containing autoclaved soil. Two month old seedlings were transplanted @ one 
seedling per pot containing 1 kg sterilized soil. Two weeks after transplanting, 
inoculation of nematode T semipenetrans @ 5000 larvae/pot and VAM fungus G. 
mosseae infested soil (20 spore/g) @ 100 g/pot were given in following combinations : 
i) nematode alone, ii) VAM fungus alone, iii) nematode+VAM fungus simultan- 
eously, iv) nematode 20 days prior to VAM fungus, v) VAM fungus 20 days prior to 
nematode, vi) no inoculum (control). With five replicates of each treatment, the 
experiment was terminated six months after inoculation. 

Growth parameters, viz,, length, fresh and dry weights of root, shoot and stem 
diameter of the seedlings inoculated with G. mosseae were greater than seedlings 
inoculated with nematode(r. semipenetrans) alone, with different combinations of 
nematode and VAM fungus and non-inoculated control. Seedlings with simultaneous 
inoculation of nematode and fungus had better growth than seedlings inoculated with 
nematode alone, nematode inoculated 20 days prior to fungus and uninoculated 
control. 

Multiplication of T. semipenetrans as indicated by population build up in roots 
and soil was highest in pots containing seedlings inoculated with nematode alone. In 
combined inoculation of nematode and fungus, higher population was recorded in 
pots containing seedlings having nematode inoculation 20 days prior to VAM fungus 

[ H8 ] 



than fungus inoculated 20 days prior to nematode and simultaneous inoculation. 
Mycorrhizal density of G. mosseae was statistically at par in seedlings inoculated with 
fungus alone, fungus inoculated 20 days prior to nematode and simultaneous inocu- 
lation of both organisms. Seedlings inoculated with nematode 20 days prior to fungus 
had lowest mycorrhizal density. 

On the basis of growth pattern it is apparent that G. mosseae had stimulatory 
effect on the growth of C. jambhiri seedlings, while T. semipenetrans had suppressive 
effect. In simultaneous inoculation of nematode and fungus, the adverse effect of 
nematode was partly neutralised and fungal symbiont limited the development of 
nematode. Similar finding were earlier reported by O'Bannon et al. (1979). While 
studying the effect of G. mosseae and T. semipenetrans on Citrus limon seedlings. This 
is evident from the fact that low population build up of nematode was observed in 
the seedlings receiving simultaneous inoculation of nematode and fungus. This 
seemed to be due to quick penetration and colonization of fungus in roots as 
compared to nematode penetration and establishment of feeding sites. Nematodes 
inoculated 20 days prior to fungus got enough time to penetrate and establish on the 
root system leaving little space for fungus to spread mycelium within root tissues. In 
such cases fungal capability to enhance growth was subsided by nematode as is 
evident from low mycorrhizal colonization and high nematode population build up. 
This phenomenon was inversed when fungus was inoculated 20 days prior to nema- 
tode. Once fungus penetrated roots and established itself in root system, perhaps it 
becomes difficult for nematode to multiply fast and exhibit the adverse effect on 
growth. Fox and Spasoff (1972) reported similar observations while working on 
interaction of Heterodera solanacearum and Endogone gigantea on tobacco. 

From the present study it can be concluded that VAM fungus G. mosseae can 
provide substantial check on citrus nematode infesting citrus root stock. However, 
field application of fungus for the control of citrus nematode needs to be worked out 
in detail. 

REFERENCES 

Baghel, P. P. S , Bhatti, D. S , Singh, I. S. 1980. Occurrence of phytonematodes on some citrus 

root-stocks. Haryana J. Hort. Sci. 9 : 131-137. 
Baghel, P. P. S. 1985. Occurrence of mycorrhizal fungus and Aphelenchns avenae on some citrus 

root-stocks. Indian J. Nematol. 15 : 280. 
Fox, J. A., Spasoff, L. 1972. Interaction of Heterodera solanacearum and Endogone gigantea on 

tobacco. J. Nematol. 4 : 224-225. 
Nemec, S. 1978. Response of six citrus root-stocks to three species of Glomus, a mycorrhizal fungus. 

Proc. Fia. State Hort. Sci. 9:1. 
O'Bannon, J. H., Inserra, R. M. N.mec, S., Vovlas, N, 1979. The influence of Glomus mosseae 

on Tyknchulus semipenetrans infested and uninfected Citrus limon seedlings, J. Nematol. 

11 : 247-250. 

C H9. ] 



Responses of dual inoculation with Bradyrhizobium and VA 
mycorrhiza or phosphate solubilizers on soybean in moliisol 

H. P. SINGH 

Deptt. of soil Science, College of Agriculture, G. B. Pant Univ. of Agric. and Tech., 

Pantnagar, Distt . Nainital-263145, India 

Inoculation with VA myconliizal fungi (Singh and Varma, 1988), efficient 
strains of Rhizobium (Chandra and Pareek, 1985) and phosphate solubilizing microor- 
ganisms (Gaur, 1985) separately and in dual form (Singh and Singh, 1988) have 
increased nodulation, dry matter accumulation in plant, nitrogen fixation and grain 
yield through better uptake of nutrients because of increased activities of soil 
microorganisms in the rhizosphere region. The present study was, therefore, under- 
taken to find out inoculation responses in terms of nodulation, plant growth and 
grain yield of soybean in a Moliisol using inoculants of Pseudomonas striata, Bacillus 
polymyxa, indigenous VA mycorrhiza, Glomus fasciculatum, Bradyrhizobium jqponicuM 
and their few main dual combinations. 

As a result of increased activities of microorganisms in the rhizosphere region 
either directly or indirectly, inoculation with Bradyrhizobium, VAM and phosphate 
solubilizers individually increased the number and dry weight of root nodules and 
organic matter accumulation in plant. Increase in the grain yield due to individual 
inoculation with Bradyrhizobium, VAM and phosphate solubilizers ranged 8.66 to 
13.82%, 0.0 to 46.55% and 0.0 to 41.38% respectively. Dual inoculation with 
Bradyrhizobium japonicum and VA mycorrhiza or phosphate solubilizers did not 
show significant increase in any of the parameters studied. The efficacy of multi 
strains inoculum of phosphate solubilizers was almost similar to the single- 
strain inoculum. 

Thus, based on the results, it may be concluded that, even in high phosphate 
soils, inoculation with single-strain inoculum of Bradyrhizobium or VAM or phosphate 
solubilizers is an essential technique for the successful cultivation of soybean. 

REFERENCES 

Chandra, R„ Pareek, R. P. 1985. Role of host genotype in effectiveness and competitiveness of 
chickpea (Cicer arietinum L.) Rhizobium. Tropical Agriculture 62 : 90-94. 

Gaur, A. C. 1985. Phosphate solubilizing microorganisms and their role in plant growth and 
crop yields. Proc Nat. Symp. in Soil Biology, Hisar, pp. 125-138. 

[ 120 ] 



Singh, H. P., Singh, T. A. 1988. Influence of VAM and phosphate solubilizers on phosphate 
solubility and growth of maize (Zea mays L.). Mycorrhiza Round Table, Proc. Work- 
shop, New Delhi, March 13-15, 1987. 

Singh, K., Varma, A. 1988. Mycorrhizal fungi, legume growth and root nodulation in dry arid 
soils. I. Effect of dual infection of Rhizobium and VA endomycorrhizal spores on 
a tropical legume-bengal gram (Cicer arietimtm L.). Mycorrhiza Round Table, Proc. 
Workshop, New Delhi, March 13-15, 1987. 



t 121 ] 



Clonal selectivity in Populus deltoides for vesicular arbuscular 
mycorrhizal association 

O. P. SIDHU, P. N. MISRA AND H. M. BEHL 

Biomass Research Centre 

National Botanical Research Institute 

Lucknow-226 001 ' 

In view of the ever increasing demand for wood, fast growing tree species like 
poplars have attracted worldwide attention. Poplars belong to the genus Populus of 
the family Salicaceae. Their wood is in much demand for paper, pulp, plywood, 
veneer, matchwood, packing cases, fibreboard and light construction timber all over 
the world. Attempts are being made by the Uttar Pardesh Forest Department to 
select suitable clones for sites below 28 latitude. Several Populus clones are under 
trial on partially reclaimed alkaline soil site at Banthra Research Station of National 
Botanical Research Institute, Lucknow. 

Endomycorrhizae often improve the quality of the nursery seedlings. Since 
Populus is multiplied by cuttings raised in nursery, association of vesicular-arbuscular 
mycorrhizal fungi can improve the growth and performance of the nursery grown 
cuttings. There have been reports of formation of endomycorrhizae in Populus 
species in Iowa (USA) soils (Walker, 1980). However, there has been no systematic 
study of VAM association in Populus deltoides particularly on marginal soils in 
India. 

Nine clones of Populus deltoides (59-101, ST-148, 15-29, 55-264, D-121, S7C15, 
S7C20, G-48 and AST-242) growing at Banthra Research Station of the institute 
were screened for association of VAM fungi. These clones were initially obtained 
from U.P. Forest Department nursery at Lalkua (elevation 256m). Soils where 
cuttings were grown are alkaline (pH=8.53 and EC=0.24 mmhos/cm) with moisture 
content ranging from 7.5 to 18.2%. 

Only three clones (15-29, ST-148 and 59-101) out of the nine clones 
investigated were found to form endomycorrhizae. Two VAM species were found to 
colonize the roots of these three clones. These fungi were identified as Glomus 
intraradices Schenck and Smith and Scutellospora gigantea (Nicol. and Gerd.) Gerd. 
and Trappe (Schenck and Perez, 1987; Trappe, 1982). Though all the soil 
samples had spores of Glomus intraradices and Scutellospora gigantea only these 
three clones formed mycorrhizae. Out of the three mycorrhizal clones ST-148 
which is a hybrid of Populus deltoidesxP. tricocarpa had the least root infection 

[ ;m--] - 



(30%) and only 8.5% of the cortex area was infested. On the other hand clones 
59-101 and 15-29 had 70% and 40% infestation, respectively. 

S7C15 and S7C20 have been reported to be fairly promising at Ialkua nursery 
(Personal communication). However, these clones didnot form mycorrhizae with the 
reported VAM species and thus no correlation between performance and VAM 
association could be established. 

The study revealed that there is a preference in mycorrhizal infection amongst 
the 9 clones of Populus deltoides grown at alkaline sites. Even amongst the three 
mycorrhizal clones there is a variation in the root infection even when relatively 
abundant spore population of the two VAM species was available in the soil. 
Certain clones where no VAM association was observed cannot be regarded as non 
mycorrhizal until a controlled experimentation by inoculating other potential 
mycorrhizal species is tried. 

Selectivity in mycorrhizal formation in other Populus hybrids being cultivated 
in USA has also been reported by Schultz cr a/. (1984). This selectivity should be 
identified for the most important clones available so that proper inoculum can be 
used for producing healthy propagules. Although some hybrids seem to show 
autotrophic growth without mycorrhizal development, potential for mycorrhizal 
formation should be established for all hybrids. Selection of appropriate VAM fungi 
and regulation of cultural practices such as site preparation and application of 
herbicides for weed control are important consideration in order to improve the 
quality of the seedlings and promote the growth of poplars. 

REFERENCES 

Schenck, N. C, Perez, Y. 1987. Mannual for the identification of VA-mycorrhizal fungi. 

University of Florida, Gaineville, Florida, USA. 
ScBultz, R.C., Isebrands, J. G., Kormanik, P.P. 1984. Mycorrhizae of poplars, Journal paper 

of Iowa Agr. and Home Economics Experiment Station, Ames, Iowa. In : Intensive 

Plantation Culture : 12 Years Research USDA Forest Service Technical Report 

NC 91, USA. 
Trappe, J. M. 1982. Synoptic key to the genera and species of Zygomycetous mycorrhizal fungi. 

Phytopathology 72 : 1102-1108. 
Walker. C. 1980. Hybrid poplar mycorrhizae and endogenous spores, unpublished Ph.D. 

desertation. Iowa State University, Ames, Iowa, USA. 



t 123] 



Interactions between isolates of ectomyrrhizal Laccaria spp. and 
root rot fungi of coniffers 

K. SAMPANGIRAMAIAH AND R. PERRIN 

Department of plant Pathology, UAS, GKVK Campus, 

Bangalore-560 065 India 

The protection of roots by ectomycorrhizal fungi against soil borne diseases 
has received considerable attention in recent years. Laccaria spp. are ubiquitous 
fungi occurring in diverse forest habitats forming ectomycorrhizal association with 
many forest trees (Shaw and Molina 1980). Isolates of Laccaria sp. protected young 
seedlings of Norway spruce (Picea abies Karst) and Douglas-fir (Pseudotsuga menziesii 
(Mirb.) Franco) from Fusariunt oxysporum Schlecht., the causal agent of damping off 
and root rot of conifers (Sampangiramaiah et al, 1985). In the forest nurseries, 
other than F. oxysporum, Pythium spp. and Khizoctonia solani are the universal soil 
borne pathogens co-existing in several forest nurseries (Sampangiramaiah and 
Perrina, 1988). 

Isolate variability in inoculum effectiveness of ectomycorrhizal fungi is 
reported with species and strains within the same species differring in their beneficial 
effects and root protection (Trappe, 1977). This necessitates the need for evaluating 
several strains or ecotypes of each fungus before selecting the performing isolates. 

The present study investigates the variability in-vitro by three isolates of 
Laccaria sp. and one isolate of L. bicolor in the suppressive influence on an isolate 
each of Fusarium oxysporum, Rhizoctonia solani and Pythium sp., the principal root 
pathogens of conifer nurseries. 

In the paired culture tests on agar plates, all the four isolates of Laccaria sp. 
did not show any substantial growth inhibition off. oxysporum. Mycelial inhibition 
was comparatively pronounced with Pythium sp. and R. solani (15-28%) especially 
with L. bicolor on Pythium sp. In general there was no substantial inhibition of 
hyphal elongation of these pathogens. 

The cell free sterile extracts of all the Laccaria sp. showed appreciable 
reduction in the mycelial dry weight off. oxysporum (30%) but not so with Pythium 
sp. and R. solani. Extracellular extracts of individual mycorrhizal isolates had 
varied effects with few having stimulatory effect on mycelial growth of Pythium sp. 
and R. solani. Extracellular metabolites of Laccaria sp. had an inhibitory effect on 

[ 124 ] 



the germination of chlamydospores of F. oxysporum (30 to 35%) although few isolates 
had no effect or slight stimulatory effect. 

Commercial preparations of two volatile organic constituents (terpenes in 
ectomycorrhizal root systems of conifers), L-pinen and Limonene were evaluated 
in-vitro on mycelial growth inhibition of the root pathogens. Both the terpenes in 
their gas phase had inhibitory effect on growth of F. oxysporum, Pythium sp. and 
R. solani when used at cone, of 0.005 and 0.05%. The inhibition ranged from 5 to 
40% with the pathogens differing in their tolerance to individual compounds. 
Pythium sp. was very sensitive to both the compounds (36 to 38% inhibition), while 
R. solani being least sensitive (13 to 16%) but, F. oxysporum was intermediate in its 
response (15 to 20% inhibition). 

The suppressive influence of four isolates of Laccaria sp. on principal forest 
nursery pathogens, Fusarium oxysporum, Pythium sp. and Rhizoctonia solani were 
investigated. The mycelial growth of these pathogens and chlamydospore germi- 
nation of F. oxysporum was partially inhibited by the metabolites liberated into the 
culture filtrate by isolates of Laccaria sp. Isolate variability in suppressive influence 
was observed with few cell free extracts stimulating mycelial growth. Thus, extra- 
cellular metabolites are considered un-important in the mechanisms of suppression. 
Commercial preparations of the terpenoid constituents of conifer root system 
(L-pine and Limonene) gave substantial inhibition of hyphal elongation of these 
pathogens. Induced host response through production of toxic metabolites (terpenes) 
in root system (Sampangiramaiah and Perrina, 1989) are well known to inhibit both 
mycorrhizal and root pathogenic fungi and this may be the chemical basis of root 
protection by Laccaria spp. 

REFERENCES 

Perrin, R., Sampangiramaiah, K. 1986. La fonte de semis en pepinieres forestieres (In French). 

Eur. J. Forest Pathol. 16 : 309-321. 
Sampangiramaiah, K.. Perrin, R., Letacon F. 1985. Disease supression and growth promotion 

of Norway spruce and Douglasfir seedlings by ectomycorrhizal fungus, Laccaria laccata 

forest nurseries. In : Mycorrhizae : Physiology and genetics, Ed. Gianinazzi- 

Pearson, INRA, PARIS, pp. 799-806. 
Sampangiramaiah, K., Perrin, R. 1989. Volatile organic constituents in ectomycorrhizal roots 

of Picea abies and induced resistance to Fusarium oxysporum. (In press). 
Shaw, G. C, Molina, R. 1980. Formation of ectomycorrhizae following inoculation of 

containerized sitka spruce seedlings. U. S. D. A. For. Serv Res., Note. PNW, pp. 351. 
Trappe, J. M. 1977. Selection of fungi for ectomycorrhizal inoculation in nurseries. Ann. Rev. 

Phytopathol. 15 : 203-222. 



[ 125 ] 



Studies on the growth of certain ectomycorrhizal fungi in culture 
media and in the host under axenic conditions 

M. RANGARAJAN, R. NARAYANAN, D. KANDASAMY AND G. OBLISAMI 

Department of Agricultural Microbiology, 

Tamil Nadu Agrl. University, Coimbatore-641003 

For understanding the physiology of ectomycorrhizal association with Pinus 
species, it is essential to know the growth requirements of the fungi under in vitro 
conditions as influenced by different media. Similarly it is also an important 
prerequisite before certain fungus is recommended for artificial inoculation, to find 
out the behaviour of different ectomycorrhizae on a Pinus species under axenic 
conditions. Although several studies have been made on the growth and nutritional 
requirements of ectomycorrhizae such as Scleroderma bovista and Cenococcum geophy- 
llum (Thaper, 1989), growth studies in vitro and in vivo, of certain fungi such as 
Amanita muscaria, Rhizopogon sp., Laccaria laccata etc. as occurring in Nilgiris region 
has not been made. Hence studies were carried out and the results reported herein. 

The ectomycorrhizal fungi isolated from Pinus roots were cultured in 3 diffe- 
rent media for studying their characters. The three media which were used in the 
study include : Modified melin Norkran's medium (MMN), Norkan's medium (NM) 
and Hegem's medium (HM). 

The fungi were cultured in agar as well as liquid media and the growth was 
assessed in terms of fungal dry weight and colony diameter. 

The pure culture synthesis techniques of Molina and Palmer (1982) were 
adopted using glass synthesis tubes of 38x300 mm filled with 110 ml of vermiculite 
and 10ml of peatmoss, which were autoclaved. Test fungus, grown for 3 weeks was 
inoculated. Uninoculated set served as control. 

Typical ectomycorrhizal synthesis was completed at 4 to 6 months after 
inoculation depending on the growth rates of fungus and host. During the synthesis 
test a small bit of substrate was aseptically removed from the vessel, transferred into 
nutrient agar, incubated and checked for contamination and reisolation of the 
original fungus. The seedling was removed intact from the synthesis vessel and its 
root&gently washed free of substrate with tap water. The entire root system was 
than placed under water in a Petri dish and observed with a stereomicroscope for 
ectomycorrhizal colonization. 

[ 126 ] 



The different ectomycorrhizal fungi such as Amanita muscaria, Hebeloma 
crustuliniforme, Laccaria laccata, Rhizopogon luteolus and Suillus brovinus and S. 
granulatus were tested for their growth characteristics in three different media with a 
view to assess the suitability of an appropriate medium for mass multiplication. 
The results revealed that among the three media tested, MMN was found to be the 
best in terms of colony diameter and dry weight of fungi produced when compared 
to NM and HM media. 

Pure culture synthesis studies were carried out to understand the effect of 
different ectomycorrhizal fungi viz., Amanita muscaria, Rhizopogon, Laccaria laccata, 
Scleroderma verrucosus and Pisolithus tinctorius on the growth of Pinus caribcea 
under axenic conditions. The results revealed that in control plants where mycorr- 
hizae were not inoculated, 5 plants out of 6 died and the remaining one also recorded 
comparatively lesser growth. Nearly 80% of plants, on the other hand, inoculated 
with ectomycorrhizal fungi survived indicating thereby the essentiality of the fungus 
in the establishment of Pinus. Among the different fungi, Pisolithus tinctorius 
recorded maximum shoot and root length and the biomass followed by Rhizopogon. 

REFERENCES 

Molina, P., Palmer, J. G. 1982. In : Methods and Principles of mycorrhizal Research. Ed. 
N. C. Schenck, Am. Phytopathol. Soc. St. Paul, USA, pp. 115-129. 

Thaper, H. S. 1989. Nutritional studies of ectomycorrhizal fungi of chirpine in culture. In : 
Mycorrhizae for Green Asia. Eds. A. Mahadevan, N. Raman, K. Natarajan, Centre 
for Advanced Studies in Botany, University of Madras, Madras, pp. 179-183. 



[ 127 ] 



The mycorrhizal association of morels in N. W. Himalayas 

ONKAR SHAD, ANAND SAGAR AND T. N. LAKHANPAL 

Department of BioSciences, Himachal Pradesh University 

Summer Hill, Shimla-1 7 1 005, H. P. 

Morels had been so far regarded either parasitic (Robert, 1985) and or 
saprophytic (Heim, 1984). Only recently they have been reported to enter into 
mycorrhizal relationship with some plant species (Buscot and Roux, 1987). These 
observations are extremely important in understanding the nutritional relationships 
of morels and the whole question needs to be reinvestigated giving due consideration 
to the mycorrhizal partner. The present studies were undertaken to study the 
mycorrhizal association of different morel species, collected from N. W. Himalayas, 
which were seen to enter into such an association. 

Three species of morels, viz. Morchella deliciosa Fries, M. esculenta (L.) Pers. 
and M. conica Pers. were observed to enter into mycorrhizal relationship with 
different plant species. Mycorrhizal connections were established by digging the 
soil and tracing the roots of the plants to the fructifications following Young (1940) 
and Zak (1973). The roots of associated plants were thoroughly washed in tap water, 
fixed in formalin, acetic acid and alcohol (70%) in the ratio of 5:5:90 for 24 hours 
and then preserved in 70% alcohol. In order to confirm the formation of mycorrhiza, 
both stained and unstained sections were prepared and examined microscopically. 

The ovservations for the mycorrhizal link between the sporocarps of the tree 
morel species and the roots of associated plants i.e. strawberry, grasses and fern 
rhizomes, were made visually. The sporocarps were taken out carefully and freed 
from soil particles by a gentle stream of tap water. The subterranean portion of the 
carpophore was seen to form a loosely woven cord near its base, which gradually 
transformed into a more compact and shapely cord, producing some short roots on 
way, and tapering at the distal end, and there getting connected to the farther end 
of the roots of these plants, forming a 'mycorrhizal bridge'. 

Anatomical observations made on sections stained with cotton blue show that 
morel hyphae penetrate into all the tissues of the root except xylem. The hyphae 
penetrate into the cells where they mostly grow near the cell wall but they also some- 
times grow deeply within the lumen. The root hairs were seen in very few sections. 
The typical fungus mantle was absent. The hyphae have not been seen to grow 
intercellularly. In longisections of the root, the hyphae were seen to form a loose 
weft on the root periphery; some of them penetrating directly into the cell lumens. 

[ 128 ■] 



Short roots also showed a similar structure and they were almost evenly distributed 
all along the long root and its branches. 

Buscot and Roux (1987) reported M, rotunda (Per.) Boud. to from mycorrhiza 
with many tree species and herbaceous plants. During the present study none of 
the species collected has been seen to enter into mycorrhizal relationship with any 
of the tree species, although they were all collected from the forested areas. As 
discovered in the present study, Buscot and Roux (1987) also had observed the 
ascocarps of M. rotunda to be joined by subterranean hyphal systems, the "mycelial 
"muffs", surrounding living roots of various plants. They also mention the presence 
of conspicuous "mycelial muffs" on the subterranean parts of stems of young trees, 
not seen in the present study. They attach great importance to these mycelial muffs 
and according to them the organs to which the "muffs" are attached always belong 
to the living plant, roots contain sap and their absorptive extremities are always 
functional. They record that the hyphae constituting the muffs are more compacted 
than in the connective mycelium and that the mycelial muffs do not induce morpho- 
logical modification in the roots or stem which it surrounds. They further emphasize 
that this together with the localization of the muffs on parts of roots that are non 
absorptive, suggests that the association is not truely mycorrhizal. However, the 
association that we have observed during the present studies seems to be doubtlessly 
truely mycorrhizal as the fungus has been seen to be associated with young absorbing 
roots. But the significance of the "muffs" needs to be ascertained in relation to 
nutrition and ascocarp formation. May be the clue for artificial cultivation of 
these fungi is revealed by such studies. 

REFERENCES 

Buscot, F., Roux, J. 1987. Association between living roots and ascocarps of Morchetta otunda. 

Trans. Brit. Mycol. Soc. 89 : 249-252. 
Heim, R. 1984. Champignons d 'Europe, 2nd edn., Paris: Societe nouvelle des editions Boubee. 
Robert, E. 1985. Relations entre la famille des Oleinees et les morilles. Bulletin de la Seiete 

botanique de France 12 : 244-246. 
Young, H. E. 1940. Mycorrhizae and growth of Pinus and Araucarta. The influence of different 

species of mycorrhiza forming fungi on seedling growth. Aust. Inst. Agric. Sci. 6 : 21-i5. 
Zak, B. 1973. Classification of ectomycorrhizae. In : Ectomycorrhizae, Ecology and Physiology, 

Eds. G. C. Marks, 7\ T. Kozlowski, Academic Press, New York, pp. 43-78. 



C 129 ] 



Relative efficacy of VAM isolates for green gram under water 
stress conditions 

HARBANS KAUR KEHRI AND SUDHIR CHANDRA 

Department of Botany, University of Allahabad 

Aliahabad-211002 

Low level of soil moisture may reduce the phosphate diffusion in plants 
(Bieleski, 1976). VA mycorrhiza may improve the water relations in plants and 
ensure a better phosphate nutrition (Puppi etal, 1988). Several authors have 
reported the mycorrhizal association in plants in relation to soil moisture level 
(Allen and Bossalis, 1983; Ponder, 1983). VAM fungi can adapt to a wide range of 
soil water regimes and may thus be exploited for improving the performance of crops 
under drier areas. The purpose of present study was to select efficient endophytes 
which could be exploited for improving the performance of green gram under 
drier conditions. 

A number of VA mycorrhizal fungi collected from local fields under legume 
cultivation (GM, NS, 4S, IWC, 7MY, OBS, ST, IS) were compared with Glomus 
fasciculatum (Thaxter sensu Gerd.). Gerd. and Trappe and G. macrocarpum Tull. 
and Tull. for their efficacy in improving the performance of two cultivars of green 
gram (T-44 and Pusa Baisakhi) under normal (20% soil moisture) and strained (5% 
soil moisture) water schedules. 

The crops were raised under greenhouse conditions in earthen pots in unsteri- 
lized field soil separately supplemented with different VAM fungi. Different water 
schedules were followed to maintain 20% and 5% soil moisture in the pots. Soil and 
root samples were collected at regular intervals and processed for estimating the 
mycorrhization. Data on nodulation, root/shoot biomasi? and yield were also collec- 
ted and analysed statistically. 

Out of 10 VAM fungi evaluated, only 4 including G . fasciculatum and three of 
the local isolates (GM, NS, and OBS) caused an improvement in the mycorrhization 
in cvr. T-44 raised under normal supply of water. Out of these only two viz. G. 
fasciculatum and isolate OBS showed alround verstality in improving the performance 
of the cultivar in terms of yield, nodulation and root/shoot biomass. Isolate NS 
caused an improvement in the yield and nodulation but failed to make an appreciable 
change in root/shoot biomass. Further, isolate GM raised the mycorrhization 
status of the crop but failed to make a positive effect on its performance. Interestin- 

[ 130 ] 



gly, inspite of its failure to raise mycorrhizal status or nodulation in the crop, isolate 
IS caused an improvement in yield and root biomass. 

The mycorrhization status of other cultivar raised under normal level of water 
supply was improved by only isolate IWC. An improvement in yield was also 
recorded due to inoculation of this fungus. Inspite of their failure to raise the 
mycorrhization status, G. fasciculatum as well as isolates NS and OBS caused an 
overall improvement in the performance of the cultivar. The behaviour of isolate 
7MY was interesting since it caused an improvement in yield but failed to improve 
either mycorrhization or nodulation. 

The response of both the cultivars to various VAM fungi under water stress 
condition also varied with the isolates. T-44 responded positively to isolate NS 
showed improved mycorrhization and performance in terms of yield, nodulation 
and root/shoot biomass. G. fasciculatum and isolate OBS improved the overall 
performance but failed to improve the mycorrhizal status. Isolates GM, IWC and 
7MY also failed to improve the mycorrhization status, however, two of them (GM 
and IWC) caused an improvement in the yield and nodulation while the third one in 
yield and root/shoot biomass. 

In all, 5 isolates including G. fasciculatum caused an improvement in the 
mycorrhization in Pusa Baisakhi raised under water stress conditions. However, only 
G. fasciculatum and isolate OBS showed an alround verstality in improving the 
performance of the cultivar. Isolate 7MY caused improvement in yield and root 
biomass, isolate ST only in yield while isolate GM only in root biomass. Inspite of 
its failure to raise the mycorrhization status of the cultivar, isolate NS also proved 
efficacious in improving its overall performance 

Superiority of introduced VAM fungi in comparison to indigenous ones in 
improving the performance of crops has been reported earlier (Powell, 1976). 

Variations in the response of different isoiates to the crop under a particular 
water schedule were evident in our study. Similar variations have been earlier repor- 
ted (Carling and Brown, 1980; Raja et ah, 1987). Such variations could be safely 
attributed to the intrinsic ability of the isolates to explore more soil area, plant-fungal 
compatibility and interaction between the endophyte and soil environment. 

Improvement in the performance of the crop due to introduced VAM isolates 
was coupled with an improvement in its mycorrhization status. However, in certain 
cases, an isolate improved the performance but failed to cause an improvement in 
mycorrhization status. At the same time, in certain other cases, an isolate failed to 
improve the performance of the crop, inspite of its ability to raise its mycorrhization 
status. 

[ 131 1 



The present study has revealed that out of 10 isolates evaluated, three isolates 
including G.fasciculatum and two locals (NS and OBS) were uniformally efficacious 
for both the cultivars under both the water schedules. They may be exploited for 
improving the performance of green gram under irrigated and rainfed regions. 
However, before employing them for practical application, it is necessary to establish 
their efficacy under field conditions. 

REFERENCES 

Allen, M.F., Boosalis, M. G. 1983. Effects of two species of vesicular arbuscular mycorrhizal 

fungi on drought tolerance of winter wheat. New Phytol. 93 ; 61-iZ. 
Bieleski, R. L. 1976. Passage of Phosphate from soil to plant. In : Reviews in Rural Sciences III 

Prospects for improving efficiency of phosphorus utilization, Ed. G. J. Blair, University 

of New England, Armidale, Australia 124. 
Carling, D. E., Brown, M. F. 1980. Relative effect of vesicular arbuscular mycorrhizal fungi on 

the growth and yield of soybean. Soil Sci. Am. J. 44 : 528-532. 
Ponder, F. 1983. Soil moisture levels and mycorrhizal infection in black walnut seedlings. Commun. 

in Soil Sci. Plant Anal. 14 : 507-511. 
Powell, C. L. 1976. Mycorrhizal fungi stimulate clover growth in New Zealand hill country soils. 

Nature 264 : 436-438. 
Puppi, G., Sanvito, A., Tabacchini, P., Bras, A. 1988. Nutrient and water relation of mycorrhizal 

white clover, 2nd European Symp. on mycorrhizae, Prague, Czechoslovakia, pp. 82. 
Raja, N. U., Sundaresan, P., Gunasekaran, P, 1987. Improved growth of cowpea by various 

isolates of VA mycorrhizal fungi. Proc. Nat. Workshop, JNU, New Delhi, pp. 313-321. 



[ 132 J 



Effect of interaction between VA-mycorrhizae and graded levels of 
phosphorus on the growth of papaya (Carica papaya) 

T. M. ROSALIND "ADMA AND D. KANDASAMY 

Department of Agricultural MicrobioJagy, 

Tamil Nadu Agricultural University, Coimbatore-641 003 

In many tropical soils, lack of phosphate is the most important constraint to 
plant growth. Research in the past years has proved that VA-mycorrhizae (VAM) 
can improve the plant growth through increased uptake of phosphorus and other 
mineral nutrients especially in low fertile soils. It is said that nearly 80-85 per cent 
of P we apply is made unavailable to plants because of their inaccessibility, fixation 
and immobilization. There has been a keen interest to show that VAM inoculation 
can increase the recovery of phosphatic fertilizer from soil by plants, ft is suggested 
that the mycorrhiza are able to explore the soil more thoroughly and hence are able 
to locate and use the point source of P. Experiments were conducted to find out the 
optimum level of P to which VAM can be combined to get maximum growth of 
papaya (Carica papaya) plants. 

Pots of size 30 x 30 cm were filled with soil (red loam; pH 7.0; EC 0.61 
m. mhos/cm 2 ; available N 250.5 kg/ha; available P 16. 1 kg/ha) and one hundred 
gram of mixed inoculum of VAM (Glomus mosseae+G. fasciculatum+Gigaspora 
margarita) was placed 2.5 cm below the seeds which contained a spore load of 
350 per 100 g of soil. The following treatments were imposed in a completely rando- 
mized block design with twenty replications : (i) control (no VAM; no fertilizer), 
(ii) VAM alone (iii) 100% of recommended level of P (iv) 100% of recommended 
level of P+VAM (v) 75% of recommended level of P (vi) 75% of recommended 
level of P+VAM (vii) 50% of recommended level of P and (viii) 50% of recommen- 
ded level of P+VAM. 

The recommended doses of N and K (250 : 200 g/pot) were applied to all 
pots in the form of urea and muriate of potash, respectively. The recommended 
(200 g/plant) or graded levels of P was applied as basal in the form of super 
phosphate. 

Four seeds per pot were sown, after applying the VAM inoculum. Usual 
agronomic practices like watering, weeding, thinning etc., were carried out. The 
biometric observations like plant height, number of leaves, shoot and root dry weight 
were taken on 90th day after sowing. The VAM colonization in roots, VAM spore 
population in soil, total nitrogen and phosphorus content of plant samples were 
determined. 

[ 133 ] 



The results revealed that among the different levels of P, 75 percent of the 
recommended level of P+VAM significantly enhanced the growth of papaya than 
the other P levels, thus indicating the optimum dose for the crop. For instance, 
there was an increase in height of plants by 25.47 per cent by application of 75% of 
P along with VAM over its respective control (75 per cent P alone). The biomass 
production and number of leaves were also increased by VAM application and the 
increase was maximum when VAM was inoculated along with 75 per cent of the 
recommended level of P. The increase in N and P contents of plants was higher by 
VAM application along with 75 per cent P and was least with 100 per cent P. The 
N content of plants inoculated with VAM at 75 per cent of recommended level of 
P was increased by 23.32 per cent on 90th day over that of the plants applied with 
75 per cent P alone. By application of VAM along with 100 per cent P there was 
only 4.65 percent increase in N content over that of the plants applied with 100 per 
cent P alone. In plant P content also, the maximum increase was recorded by VAM 
application with 75 per cent P (30.85 per cent increase). Thus the present study 
indicated that application of 75 per cent recommended level of P+VAM was 
equivalent to 100 per cent P in enhancing the growth of the plant, thus saving a 
fertilizer input of 25 per cent. 

It was also observed that there was a decrease in the intensity of VAM 
colonization when large amount of P was added to papaya seedlings. The per cent 
colonization in roots of plants inoculated with VAM along with 75 per cent of 
recommended level of P was 41.67 as against 35.0 by inoculation with VAM+ 100% 
of recommended level of P. This confirms the earlier reports of many workers 
(Stribley et al, 1980; Masse and Phillips 1971; Krishna and Dart, 1984). 
REFERENCES 

Krishna, K. R., Dart, P. J. 1984. Effect of mycorrhizal inoculation and soluble phosphorus 

fertilizer on growth and phosphorus uptake of pearl millet. PI. Soil 81 : 247-256. 
Mosse, B., Phillips, J. M. 1971. The influence of phosphate and other nutrients on the 

development of vesicular-arbuscular mycorrhiza in culture. /. Gen. Microbiol. 

69 : 157-166. 
Stribley, D. P., Tinker, P. B., Rayner, J. H. 1980. Relation of internal phosphorus concentrations 

and plants weight in plants infected by vesicular-arbuscular mycorrhizas. New Phytol. 

86 : 261-266. 



[134 ] 



Influence of VA-mycorrhizal inoculation on growth and development 
of rapeseed 

P. P GUPTA, M. L. CHHABRA, B. L. JALALI AND P. R. KUMAR 

Haryana Agricultural University, Hisar-125004, INDIA 

Various field and laboratory experiments conducted at different locations have 
demonstrated that VA-mycorrhizal inoculation can improve health and nutrition of 
crop plants (Mosse, 1973; Lin and Hao, 1988). This symbiotic relationship with 
plants also leads to biological supression of soil-borne plant pathogens (Jalali and 
Hari Chand, 1988). Investigations initiated earlier indicated positive correlations 
between VA-mycorrhizal colonization and development in mustard (Brassica juncea), 
when such plants were subjected to mycorrhizal inoculation (Jalali, 1984). The aim 
of the present study was to quantify the impact of VA-mycorrhizae on growth and 
development of rapeseed (B. campestris var. Toria cv PT-303). 

The procedures adopted by Phillips and Hayman (1970) and Jalali and 
Domsch (1975) for root-clearing & staining and assessment of mycorrhizal 
colonization respectively, were employed. The physico-chemical analysis of soil was 
carried out in mycorrhizal as well as non-mycorrhizal-inoculated soils at two stages, 
viz., at pre and post planting time. 

Available N, P, K, electrical conductivity, C.E.C. and organic carbon content 
were less in the samples taken at the time of harvesting as compared to samples 
taken before planting. Of these parameters, most significant change was observed 
in electrical conductivity. VA-mycorrhizal colonization exhibited significant increase 
in mean shoot and branch length, total dry matter production, total pod weight as 
well as yield per plant, as compared to uninoculated controls. 

Nitrogen, phosphorus and potassium contents of root and shoot increased 
significantly in mycorrhizal-inoculated plants. Among these major nutrients, maxi- 
mum response was observed in the transport of phosphorus. 

These results suggest that mycorrhizae either were themselves responsible for 
higher survival and growth of mycorrhizal inoculated plants of rapeseed or influenced 
growth by modifying chemical composition of plants. 

REFERENCES 

Jalali, B. L. 1984. Growth responses of mustard (Brassica juncea) to vesicular-arbuscular 
mycorrhizal system. In : Rapeseed-Mustard Annual Report, ICAR, pp. 323. 

[135 ] 



Jalali, B. L., Dotnsch, K. H. 1975. Effect of systemic fungitoxicants on the development of 

endomycorrhiza. In : Endomycorrhizas, Eds. F. E. Sanders, B. Mosse, P. B. Tinker, 

Acad. Press, London, pp. 525-530. 
Jalali, B. L., Chand, H. 1988. Role of VAM in biological control of plant diseases. In : 

Mycorrhizae for Green Asia, Eds. A. Mahadevan, N Raman, K. Natarajan, CAS in 

Bot. Univ. of Madras, pp. 209-215. 
LINXIAN-Gui, Hao Wen Yin. 1988. Effect of VAM inoculation on growth of several kinds 

of plants. In : Mycorrhizae for Green Asia Eds. A. Madadevan, N. Raman, K. 

Natarajan, CAS in Bot. Univ. of Madras, pp. 231-23 2. 
Mosse, B. 1973. Advances in the study of vesicular arbuscular mycorrhiza. Ann. Rev. Phytopathol. 

11 ; 171-196. 
Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing and staining parasitic 

and VA-mycorrhizal fungi for rapid assessment of infection. Trans. Brit. Mycol. Sac. 

55 : 158-161. 



[ 136 ] 



Role of endomycorrhizae in fuelwood plantation nurseries for 
alkaline soil sites 

H. M. BEHL 

Biomass Research Centre, 

National Botanical Research Institute, Lucknow-226 001 

Throughout the developing world, substandard soil sites have become relevant 
on account of paucity of good arable land. Nearly 7 million hectares of saline and 
usar land has been regarded unfit for agriculture on account of high concentration of 
soluble salts and exchangeable sodium (Khoshoo, 1987). Fuelwood plantation can 
meet the challange as the nation faces an acute firewood shortage. Many experiments 
to raise fuelwood plantations on degraded soils fail due to high mortality and poor 
establishment. Healthy and quality seedlings, though difficult to grow are a prere- 
quisite to the successful establishment of hardwood plants particularly for usar type 
substandard soil sites. Consistant nursery production of such seedlings is a major 
obstacle in implementation of fuel wood production programme on degraded soils. 

Besides rhizobia, endomycorrhizae improve the quality of seedlings in tree 
nurseries (Kormanic, 1980). Data from earlier studies show that when root systems 
are tailored in nursery with vesicular-arbuscular mycorrhizal fungi prior to planting 
the tree survival and growth improves significantly. Performance of hardwood tree 
species such as sycamore on kaolin has been improved by specific endomycorrhizal 
fungi (Marx, 1977). Only a limited research has been done on the importance of 
endomycorrhiza to plant growth. These symbionts improve the nutrient uptake, 
facilitate the uptake of moisture in plants. There is a selective ion absorption and 
accumulation especially of phosphorus and other micronutrients like Zn and Cu 
(Moawad, 1986). These fungi also increase the longivity of feeder root function and 
they persist longer on the root system than the normal roots. 

With the exception of a few species of Acacia and Leucaerta VAM affinity of 
tropical tree legumes is not fully recorded. Also there have been very few studies 
on association of ecologically adapted VAM fungi with tropical trees on degraded 
soil sites. In the tropics, where P fertilizers are expensive and where soils are often 
P deficient, VAM fungi can play an important role in improving tree productivity. 

Eight nitrogen fixing tree species : Acacia nilotica, A. niloticavar. cupressiformis, 
A. auriculiformis, Cassia siamea, Leucaena leucocephala, Parkinsonia aculata, Prosopis 
juliflora and Tamarindus indica, and certain non-leguminous tree species like Casuarina 

I 137 ] 



glauca, C. obessa, C. equisetifolia and Populs deltoides under biomass trial at Banthra 
Research Station of National Botanical Research Institute, Lucknow have been 
screened for mycorrhizal association. Dominant VAM species like Glomus fasicula- 
tum, G. intraradices, G. dimorphicum, Scutellospora calosopora and S. gigantea 
have been isolated. Their effect in promoting the growth of nursery seedlings is being 
investigated. Initial experimentation has suggested that these fungi are not only 
beneficial to growth of the seedlings, but promote the survival and growth of trans- 
planting stock (Sidhu and Behl, Unpublished). On the basis of our study the 
following considerations are significant for a research programme related to the role 
of endomycorrhiza in nurseries of hardwood tree species particularly for alkaline 
soil sites. 

A particular tree species may enter into mycorrhizal association with one or 
many different species of mycorrhizal fungi at a given time. Some mycorrhizal fungi 
have a broad tree host range whereas others have a very narrow host range. Many 
plant species like Populus deltoides have shown selectivity and preference for a 
particular species. Dominant taxa of VAM fungi should be identified for a particular 
soil site. Some species of mycorrhizal fungi are more beneficial to nursery stocks 
than others. Certain mycorrhizal fungi are more ecologically adapted to certain 
sitss than other fungi. There is an interaction between rhizobia and endomycorrhizae 
or Frankia and endomycorrhiza. It has been observed in certain cases that the 
growth of tree seedling is better with only N fixing microbe inoculum or endomycorr- 
hiza but when there is a synergistic effect the growth is relatively less pronounced. 
Hence a study of interaction of N fixing bacteria or Frankia and endomycorrhiza 
is essential. Degraded soils like usar soil sites don't have a rich flora of VAM fungi. 
Hence VAM inoculated nursery seedling is an important technology for better 
survival and establishment of tree species in usar soils. Soil fumigation often destroys 
the mycorrhizal flora. Once these symbiotic fungi have been eradicated from soil, 
reinfestation is slow. Only limited work has been done on the role of endomycorrhiza 
for fuelwood plantation and practically none on usar type degraded soils. It should 
be regarded as a thrust area of research. 

REFERENCES 

Khoshoo, T. N. 198T Ecodevelopment of alkaline land : Banthra— A case study. National 

Botanical Research Institute, Lucknow. 
Kormanic, P. P. 1980. Effects of Nursery Practices on VAM development and Hordwood seedling 

production. In : Proc. Tree Nursery Conf Sept. 2-4, Lake Barkley, KY, USA. 
Marx, D. H. 1977. The role of mycorrhizae in Forest Production. In : Proc. Annual Meeting 

TAPPI Conf, Feb. 14-16, 1977, Atlanta, GA, USA. 
Moawad, A.M. 1986. The problems of using vesicular-arbuscular (VA) mycorrhiza for supplying 

phosphate to plants. Plant Res. & Development 23 : 68-77. 



[ 138 ] 



A strategy for selection and application of VAM fungi for Glycine max 

ANITA KAPOOR AND K. G. MUKERJI 

Microbiology and Molecular Genetics Section, Tata Energy Research Institute 

7, JorBagh, New Delhi-110003; Department of Botany, 

Delhi University, Delhi 

Vesiculars arbuscular mycorrhizal (VAM) system has three components : 
plant, fungal endophyte and soil. The practical significance of this is manifested in 
screening procedures to select optimum combinations of all the three components as a 
guide to field inoculation trials. For the economical utilization of VAM on large 
scale, it is necessary to (i) characterize and identify VAM fungi, (ii) define more 
precisely VAM specificities and preferences with different host plants and (iii) amend 
soil conditions for best results. In view of the above facts the present work was 
carried out with the objective to determine growth responses of soybean inoculated 
with selected VAM fungi. 

Scanning Electron Microscopic (SEM) studies were carried out to taxonomically 
characterize the VAM fungi (G. fasciculatum, G. macrocarpum, G. multisubstensum) 
for their proper application and selection as inoculant fungi for soybean {Glycine max). 
These species were identified according to Trappe (1982). The major distinguishing 
characters as revealed by SEM were the wall layers and hyphal attachments. Spores 
of G. multisubstensum showed two inseparable wall layers and the wide attachment of 
subtending hyphae (2-4 in number) at one end of the spore; apart from the characters 
observed by light microscopy. Spores of G. macrocarpum and G. fasciculatum showed 
two distinct separable layers, but in former the inner wall was laminate whereas 
spores of G. fasciculatum showed thickened inward projections in the inner 
thicker wall. 

The effect of five VAM fungi (G. fasciculatum, G. macrocarpum, G.fuegianum, 
G. multisubstensum and G. mosseae) was observed on plant growth in terms 
of dry weight and total phosphorus. G. macrocarpum significantly influenced growth 
of soybean as compared to other inoculated VAM fungi. In terms of dry weights 
fungal effectiveness was in the order : G. macrocarpum > G. fasciculatum > 
G. fuegianum > G. multisubstensum > G. mosseae. Mycorrhizal colonization was 
maximum (85%) in plants inoculated with G. macrocarpum and minimum (48%) in 
plant inoculated with G. mosseae. Colonization was observed throughout the 
growing season, however intensity of colonization increased during final harvest. 
Dry weight, total P and colonization data clearly shows that G. macrocarpum was 

[ 139 ] 



the most efficient mycosymbiont for soybean, whereas G. mosseae was least effective. 
On the basis of the above data G . macrocarpum and G . fasciculatum were selected 
for further studies. 

The effect of different phosphorus levels and mycorrhizal inoculation was 
observed on growth of soybean in terms of dry weight and total P with the intention 
to find out the most suitable phosphorus level for this association. Plants showed 
varied response to phosphorus application (0, 0.2, 0.4, 0.6, 1.0, 1.4, 2.0, 2.8 mg/pot) 
and mycorrhizal inoculation of G. macrocarpum and G. fasciculatum individually. At 
the highest level of phosphorus, growth of both endophytes was 2.8 mg/pot. Plants 
showed greater response to mycorrhizal inoculation at intermediate levels of applied 
phosphorus. Mycorrhizal colonization decreased approximately three folds at higher 
levels of phosphorus. Total Pin the tissues was maximum (6.08 mg/pot) in plants 
inoculated with G. macrocarpum as compared to other inoculated treatments. The 
total P in the tissues of mycorrhizal plants was much more than that of control plants. 
There was higher phosphorus content in the plant tissues inoculated with 
G. macrocarpum than inoculated with G . fasciculatum and in uninoculated controls. 

G. macrocarpum was efficient VAM fungus for soybean over other VAM species 
i. e. G. mosseae, G.fuegianum, G. multisubstensum. G. macrocarpum was superior 
over G. fasciculatum at intermediate levels of applied phosphrus. SEM can be 
used as an aid in taxonomic characterization of VAM fungi. 

REFERENCE 

Trappe, J. M. 1982. Synoptic keys of the genera and species of zygomycetous (vesicular-arbuscular) 
mycorrhizal fungi. Phytopathology 72 : 1102-1108. 



C 140 ] 



Effect of different VAM fungi under varying levels of phosphorus 
on growth and nutrition uptake of pigeon pea (Cajanus cajari) 

R. S CHAMPAWAT 
Department of Plant Pathology, Rajastban Agricultural University 
S. K. N. College of Ariculture, Jobner-303329 

Mycorrhizal plants grow better in infertile soil, largely because of increased 
uptake of nutrients especially phosphorus. Mycorrhizal fungi enhance water 
transport in plants (Safir et al, 1971), help plants to withstand high temperature 
(Marx and Bryan, 1971), promote establishment of plants in wasteland (Marx and 
Artman, 1979). Pigeon pea (Cajanus cajan) plants have short and few root hairs and 
it will depend more on mycorrhiza as the volume of permeated soil is much greater 
with the hyphae of a mycorrhizal fungus than with plants root hairs, and for this 
reason many plants with short or rudimentary hairs depend more on mycorrhizae 
than do plants with finely branched roots and long and abundant hairs (St. John, 
1980). These attributes of mycorrhizae are being considered important in modern 
agriculture. Looking to Jhese facts the present study was undertaken to test 
relative performance of pigeon pea to inoculation with different mycorrhizal fungi at 
varying levels of phosphatic fertilization in pots. 

Sandy loam soil which was deficient in phosphorus (3 mg available P/kg of 
soil extracted with NH 4 F+HCL), with pH 7.8 was used. Pots of 30 cm diameter 
were filled with 5.0 kg sterilized soil. Soil was sterilized by autoclaving at 1.1 kg 
cm -2 pressure for 2 h. The VAM fungi Glomus fasciculatum (Thaxt) Gerd and 
Trappe, Glomus constrictum Trappe and Gigaspora calospora (Nicol. and Gerd.) Gerd. 
and Trappe used as inocula were maintained on Cenchrus ciliaris a perennial host 
grown in stenle soil for a period of 90 days. For VAM inoculation extramatrical 
chlamydospores and infected root pieces of Cenchrus ciliaris of the particular fungus 
(50 ml soil/pot) were layered 2 cm below the soil surface before sowing to produce 
mycorrhizal plants. Control plants did not receive any inoculum. Four different levels 
of phosphorus (0 kg P/ha, 25 kg P/ha, 50 kg P/ha and 75 kg P/ha) in the form of single 
super phosphate were applied in all the pots before sowing. Two seeds of pigeon 
pea were sown in each pot. The plants were allowed to grow in each pot, after 15 
days they were thinned to one per pot. Plants were raised in a wire-mesh house 
receiving sunlight for 12 h each day and were irrigated with sterilized water. The 

[ 141 ] 



experiment was laid out in a randomised block design consisting of 4 VAM and 4 
levels of phosphorus. Thus, in all there were 16 treatments and each treatment 
consisted 4 replications. 

Plants were harvested after 60 days. Dry weight of shoot and root were 
recorded. Per cent root colonization by mycorrhizal fungi was determined according 
to Phillips and Hayman (1970). Mycorrhizal spores in the root zone soil were 
estimated by wet sieving and decanting technique (Gerdemann and Nicolson, 1963). 
Shoot and root phosphorus was estimated by the vanadomolybdate yellow colour 
method (Jackson, 1971). The nitrogen content of the shoot and root was analysed 
by microkjeldhal method (Bremner, 1960). 

The overall growth of mycorrhizal plants was superior to non mycorrhizal 
plants at all levels of added P and plant shoot and root dry weight were increased. 
Maximum plant growth improvement was noticed at 50 kg P/ha. Among the three 
VAM fungi Glomus constrictum was superior to Glomus fasciculatum and Gigaspora 
calospora in enhancing plant dry weight at all levels of P except at 75 kg P/ha, where 
Gigaspora calospora proved to be more effective than Glomus constrictum. Significant 
increase in shoot and root phosphorus and nitrogen uptake was observed in all the 
three VAM fungi at all levels of P application. However, highest uptake of phospho- 
rus and nitrogen was observed by Glomus constrictum at 50 kg P/ha. Increase in 
phosphorus application resulted in reduction in the intensity of mycorrhizal infection 
as well as number of extramatrical chlamydospores in the soil. Maximum number 
of spores and per cent infection was recorded in Gigaspora calospora when 
no phosphorus was applied. 

Pigeon pea plants responded to all the three VA mycorrhizal inoculation, the 
response being prominent at low levels of P. The results of the present study revea- 
led that high concentration of phosphorus is detrimental to proliferation of the fungal 
symbiont and subsequent spore production. Excess phosphorus is known to reduce 
infection and spore production by Glomus in Abelmoscus esculentus (Krishna and 
Bagyaraj, 1982). Maximum beneficial effect of mycorrhizal symbiosis was achieved 
at lower levels of soil fertility. The mycorrhizal dependency is generally high at low 
levels of added phosphorus. Similar observations were made by Krishna and Dart 
(1984) in pearl millet. In pigeon pea the increase in plant dry weight and nutrient 
uptake was so pronounced that this treatment should be adopted for substitution of 
chemical fertilizer. 

REFERENCES 

Bremner, J. M. I960. Deterimination of nitrogen in soil by kjeldhal method. /. Agric. Sci. 

55 : 11. 
Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted by wet 

sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 236-244. 

[ 142 ] 



Jackson, M. L. 1971. Soil chemical analysis. Prentice Hall of India Ltd., New Delhi. 

Krishna, K. R., Bagyaraj, D. J. 1982. Effect of vesicular-arbuscular mycorrhiza and soluble 

phosphate on Abelmoscus esculentus (L.) Moench. Plant and soil. 64 : 209-213. 
Krishna, K. R., Dart, P. J. 1984. Effect of mycorrhizal inoculation and soluble phosphorus 

fertilizer on growth and phosphorus uptake of pearl millet. Plant and Soil. 81 : 247-256. 
Marx, D. H, Bryan, W. C 1971. Influence of ectomycorrhizae on survival and growth of aseptic 

seedlings of loblolly pine at high temperature. For Sci: 17 : 37-41. 
Marx, D. H., Artman. J. D. 1979. Pisoltihus tinctorius ectomycorrhizae improve survival and 

growth of pine seedlings on acid coal soils in Kentucky and Virginia. Reclamation Rev. 

2 : 23-31. 
Phillips, J, M., Hayman, D. S. 1970. Improved procedures for clearing roots and staining 

parasitic and vesicular-arbuscular mycorrhizal fungus for rapid assessment of infection. 

Trans. Brit. Mycol. Soc. 55 : 158-161. 
Safir, G. R., Boyer, J. S., Gerdemann, J. W. 1971. Nutrient status and mycorrhizal enhancement 

of water transport in soybean. Plant Physiol. 49 : 700-703. 
St. John, T. V. 1980. Root size, root hairs and mycorrhizal infection. A reexamination of 

Baylis's hypothesis with tropical trees. New Phytol. : 88 483-488. 



[ 143 ] 



Effect of superphosphate, rock phosphate as sources of phosphorus 

in combination with Glomus fasciculatum on root colonization, 

growth and chemical composition of blackgram 

G. UMA DEVI AND K. SITARAMAIAH 

Department of Plant Pathology, Andhra Pradesh Agricultural University, 

Agricultural College, Bapatla-522101 

Legumes play a major role in agriculture by providing high protein grain and 
in improving soil fertility (Manjunath and Bagyaraj, 1984). Phosphorus deficiency 
is probably the major limitation in Indian soils which have high capacity to fix 
phosphorus. Vesicular arbuscular mycorrhizae which occur widely under various 
environmental conditions are implicated to enhance phosphorus uptake and growth 
of legumes. Therefore, there has been increasing interest on the use of vesicular- 
arbuscular mycorrhiza to improve crop productivity in legumes. 

Blackgram (Vigna mungo L. Hepper) is an important pulse crop in Andhra 
Pradesh and is grown widely in rice fallows. Very little information is available 
about the blackgram and mycorrhizal symbiosis. Therefore, in this paper the effect 
of vesicular arbuscular mycorrhizal inoculation with added phosphorus on root 
colonization, plant growth and nutrition of blackgram (cv. LBG-20) is reported. 
Superphosphate and rock phosphate at three different levels viz., 0, 20 and 40 kg 
P 2 6 /ha were applied to the pots. The studies were conducted in unsterilized black 
cotton soil. 

Vesicular arbuscular mycorrhizal inoculated blackgram plants recorded higher 
per Cent root colonization over uninoculated plants although the plants were supple- 
mented with phosphorus irrespective of its source and dosage. However, the per cent 
colonization, decreased with corresponding increase in the concentration of 
phosphorus. Among the two sources of phosphorus, rock phosphate was found to 
encourage greater root colonization compared to superphosphate at 20 kg/ha. 
Earlier, Lim and Cole (1984) reported that mycorrhizal root colonization decreased 
with increase in phophorus levels in legumes. 

Mycorrhizal inoculated plants also recorded higher dry weights of root and 
shoot, total chlorophyll content compared to plants supplied with phosphorus alone. 
With the increase in the level of phosphorus a corresponding increase in the dry 
weight of shoot and root was noticed in mycorrhizal inoculated and uninoculated 
plants when phosphorus was supplied in the form of superphosphate. This is jtj 
confirmity with the observation of Mardch et al. (1967) in maize. 

[ H4 \ 



Application of phosphorus in combination with Glomus fasciculatum had 
increased effect in enhancing nitrogen, phosphorus, potassium, calcium and magne- 
sium content in blackgram plants compared to uninoculated plants supplemented 
with phosphorus alone. Krishna (1984) also reported identical observation in pea- 
nut. Super phosphate as a phosphorus source enhanced nitrogen, potassium, 
calcium and magnesium content to a greater extent compared to rock phosphate 
irrespective of its levels. But the phosphorus concentration was more in the plants 
supplemented with rock phosphate. Murdoch et al. (1967) also observed similar 
results. However, phosphorus when applied at 40 kg P a O s /ha enhanced the per cent 
nitrogen, phosphorus, potassium, calcium and magnesium irrespective of phosphorus 
sources in mycorrhizal inoculated as well as uninoculated plants. 

Inoculation with Glomus fasciculatum in combination with phosphorus 
increased per cent mycorrhizal root colonization, dry weight of root and shoot, total 
chlorophyll content and chemical contents of blackgram plants over uninoculated 
plants supplied with phosphorus alone. However, increased application of phosphorus 
decreased the per cent root colonization. Both VA mycorrhizal inoculated and 
uninoculated blackgram plants derived maximum benefit when phosphorus was 
supplied in the form of superphosphate than as rock phosphate. 

REFERENCES 

Krishna, K. R., Bagyaraj, D. J. 1984. Growth and nutrient uptake of peanut inoculated with the 

mycorrhizal fungus Glomus fasciculatum compared with non-inoculated ones. PI. Soil 

77 : 405-408. 
Lim, L L., Cole, A. L. J. 1984. Growth response of white clover to vesicular-arbuscular 

mycorrhizal infection with different levels of applied phosphorus. N. Z. J. Agr. Res. 

27 : 587-592. 
Manjunath, A., Bagyaraj, D.J. 1984. Response of pigeonpea and cowpea to phosphate and dual 

inoculation with vesicular-arbuscular mycorrhiza and Rhizobium. Trop. Agric. 

61 : 48-52. 
Murdoch, C. L , Jakobs, J. A., Gerdemann. J. W. 1967. Utilization of phosphorus sources of 

different availability of mycorrhizal and non-mycorrhizal maize. PI- Soil 27: 329-334. 



[ 145 ] 



Response of brinjal genotypes in terms of dry weight and phosphorus 
uptake as influenced by VAM inoculation 

D. V. INDI, B. K. KONDE AND K. R. SONAR 
Department of Plant Pathology and Agricultural Microbiology, 
Mahatma Phule Agricultural University, Rahuri-413 722, India 

The host genotype dependence for response to VAM inoculation has been 
shown to exist in many crops. However, the information on genotypical response of 
brinjal to VAM inoculation is lacking. A pot culture experiment was, therefore, 
conducted during rainy season (August-November) of 1988 in FCRD with three 
replications to study the response of some brinjal genotypes to VAM inoculation 
under unsterile soil conditions. The mycorrhizal seedlings of eleven genotypes viz., 
Vaishali, Manjri Gota, Pragati, Annamalai, PS-8, Dorli, Borgaon-1, Ruchira, Krishna- 
kathi, P.P. Long and Solarium writti were raised by inoculating the nursery bed (1.0 x 
3.0 m) with 5 kg inoculum of Glomus fasciculatum consisting of extramatrical 
chlamydospores (415 spores 50 -1 ml), infected guinea grass roots and the soil. The 
seedlings raised from the beds applied with uninfected soil+sand (1:1) mixture served 
as control. The 45 day old seedlings were transplanted to the pots (one seedling pot -1 ) 
containing 8 kg P deficient unsterile soil (Olsen P=3.00 ppm). The plants were 
fertilized with N, P a 6 and K a O @ 100, 50 and 50 kg ha- 1 respectively. The plants 
were harvested at 50 days after transplanting (flowering stage). The observations on 
shoot and *-oot dry weights were recorded and the P uptake was determined by 
vanadomolybdate yellow colour method (Jackson, 1971). The mycorrhizal depen- 
dency was worked out and the VAM root colonization was determined by following 
the root slide technique (Nicolson, 1960) after clearing the roots with KOH and 
staining with trypan blue (Phillips and Hayman, 1970). 

The results revealed that the per cent VAM colonization in roots of genotypes 
inoculated with G . fasciculatum varied from 48.0 to 65.33 which reflected in varied 
response of the genotypes towards the dry matter and P uptake. The shoot dry 
weights differred significantly for the genotypes and the inoculation but the interactions 
were non-significant. The genotypes, P.p. Long (7.17 g plant" 1 ) and Ruchira (7.0 g 
plant -1 ) recorded significantly higher shoot dry weight than Borgaon-1, S. writti, 
Vaishali, Dorli, Krishnakathi and Annamalai. The mycorrhizal plants across the 
genotypes recorded significantly higher mean shoot dry weights (6.57 g plant -1 ) than 
the non-mycorrhizal ones (4.20 g plant -1 ). The root dry weights differred signifi- 
cantly only for the inoculation treatments. Although the genotypes exhibited the 
non-significant differences, Borgaon-1 recorded the highest root dry weight (1.9 g 

[ 146 ] 



* 



plant -1 ). The mycorrhizal inoculation across different genotypes recorded significantly 
superior mean root dry weight (1.93 g plant -1 ) over the non-mycorrhizal ones (1.35 g 
plant -1 ). The P uptake also differred significantly only for the inoculation treatments. 
The mycorrhizal plants across the genotypes recorded significantly higher mean P 
uptake (62.01 mg plant -1 ) than the non-mycorrhizal ones (32.16 mg plant -1 ). 

The genotypes displayed varying VAM dependency as revealed through their 
shoot and root dry weights and the uptake of phosphorus. The shoot and root dry 
weights in mycorrhizal plants of various genotypes ranged from 1.20 to 3.83 times 
and 1.03 to 1.78 times respectively that of non-mycorrhizal plants. The mycorrhizal 
dependency of the genotypes ranged from 117.20 to 309.91 per cent. An increase in 
P uptake by eleven genotypes due to mycorrhizal inoculation ranged from 1.27 to 4.30 
times that of comparable controls. The results, in general, indicated a genotype- 
dependent variation in dry matter and P uptake as influenced by VAM inoculation. 

Thus the brinjal genotypes could exhibit different degrees of VAM colonization 
and differential response to inoculation in terms of their dry matter and P uptake. 
The genotypes viz., S. mini, PS-8, Dorli, Pragati and Borgaon-1 were found to be 
better VAM responsive than the others and indicated the possibility of their use in 
the plant breeding programmes. The genotypic variation in colonization and respon- 
se to VAM inoculation could be due to an interaction between the host genotypes 
and the VAM strain preferences. The number of infection sites on the roots could 
also be a factor and different levels of colonization amongst the genotypes could 
arise from differences in the rate of growth of the fungus through the root cortex 
(Smith and Walker, 1981). The study also threw light on, the need for rigorous 
screening of the available brinjal germplasm to search for the lines with high levels of 
VAM colonization for further utilization in the plant breeding programmes for 
enhanced yields. 

REFERFNCES 

Jackson, M. D. 1971. Soil Chemical Analysis. Prentice Hall of India (Ltd.), New Delhi. 
Nicolson, T. H. 1960. Mycorrhizae in the graminae II. Development in different habitats 

particularly sand dunes. Trans. Brit. Mycol. Soc. 43 : 132-145. 
Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing roots and staining 

parasitic and vesicular arbuscular mycorrhizal fungi for rapid assessment of infection. 

Trans. Brit. Mycol. Soc. 55 : 158-161. 
Smith, S E., Walker, N. A. 1981 A quantitative study of the mycorrhizal infection in Trifolium : 

Separate determination of the rates of infection and of mycelial growth. New Phytol. 

89 : 225-240. 



[ 147 ] 



Improved yields in potato through mycorrhizal inoculations 

R. P. RAI 

Central Potato Research Station, Patna-801 506, Bihar 

Growth responses to mycorrhizal inoculations have been demonstrated in 
many crops and this is attributed to the increased phosphate uptake from soil 
(Hayman, 1980). As other crops, potato also responds to mycorrhiza in terms of 
increased vegetative growth and tuber yield (Black and Tinker, 1977). In view of 
this, field experiments were carried out at Patna for two consecutive years, 1987-88 
and 1988-89 to assess the role of mycorrhiza on two potato cultivars, Kufri Sindhuri 
and Kufri Lalima. 

The inocula of Glomus masseae and G. fasciculatum were obtained and multi- 
plied on Ragi plants grown in infertile soils. The test inoculum consisted of 
mycorrhizal roots and spores and the spore-count was determined before inoculation 
in the field by plate method (Smith and Skipper, 1979). With a view to have less 
fertile soil, fields were selected which did not receive phosphatic fertilisers during 
previous two crop seasons. The soil analysis indicated the level of Organic carbon, 
available P a O B and available K 2 as : 0.35%, 27.5 and 185.0 kg/ha, respectively. 

In the RBD experiment, the mycorrhizal inoculum (8 spores/g soil) was 
applied in furrows before the placement of tubers followed by ridge formation. 
Normal irrigations were given during the crop period. At the maturity of the crop, 
the root samples were drawn and processed (Phillips and Hayman, 1970) and the 
yields were also recorded. The quantification of mycorrhization in terms of per cent 
root infection and per cent root length area infected were calculated (Biermann 
and Linderman, 1981). 

In cv. Kufri Sindhuri, the per cent root infection and per cent root 
length area infected were 48.4 and 2.74, respectively in inoculated plants whereas 
these were 28.0 and 0.20%, respectively in non-inoculated plants. Similarly in cv. 
Kufri Lalima, the per cent root infection and per cent root length area 
infected in inoculated and non-inoculated plants were 87.5 & 4.63 and 60.0 & 1.73, 
respectively. These results clearly indicated the increased level of mycorrhization 
in the inoculated plants over the noninoculated plants, however, the mycorrhization 
in non-inoculated plants is attributed to the native population of mpcorrhiza in the 
test field. 

The data on tuber yield were also comparable in inoculated and non-inoculated 
plants of both cultivars. In cv. Kufri Sindhuri, the yields were 99.01 and 93.77 



q/ha in inoculated and non-inoculated plants. In cv. Kufri Lalima, the yields 
(q/ha) in inoculated and non-inoculated plants were 96.22 and 92.26, respectively. 
Thus the mycorrhizal inoculations resulted in the increased yields in both cultivars 
to the tune of 5.5 and 4.2%, respectively. Although these increases appeared to be 
marginal but statistically significant. 

The present study has revealed that mycorrhizal applications result in the 
increased yields leading to a marginal benefit. However, there still remains a scope 
for use of selective efficient strains of mycorrhizal fungi which may in turn prove to 
be more beneficial in term of substantial increased yields. Their effects are likely to 
be more pronounced in lesser fertile or infertile soils. 

REFERENCES 

Biermann, B., Linderman, R. G. 1981. Quantifying versiclar-arbuscular mycorrhizae : A proposed 
method towards standardization New Phytol 87 : 63-67. 

Black, R. L. B., Tinker, P. B. 1977. lnteractipn between the effects of vesicular-arbuscular 
mycorrhizae and fertiliser phosphorus on yields of potatoes in the field. Nature 
267 : 510-511. 

Hayman, D S. 1980. Mycorrhiza and crop production. Nature 287 : 487-488. 

Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing and staining parasitic and 
vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Brit. 
Mycol. Soc. 55 : 158-161. 

Smith, G. W., Skipper, H.D. 1979. Comparison of methods to extract spores of vesicular- 
arbuscular mycorrhizal fungi. Soil Sci. Soc. Am. J. 43 : 722-725. 



[ 149 ] 



Studies on vesicular-Arbuscular (VA) mycorrhizal impact on growth 
and development of cowpea (Vigna unguiculata (L.) Walp) 

M. L. CHHABRA, R. P. SINGH AND B. L. JALALI 

Department of Plant Pathology, Haryana Agricultural University 

Hisar-125 004, India 

The wide spread occurrence of VA-mycorrhiza in nature and their importance 
in mineral nutrition of almost all plants have sufficiently been documented. Several 
Held, laboratory as well as green house experiments have demonstrated that VA- 
mycorrhizal colonization can greatly improve growth and nutrition of host plants 
(Mosse, 1973; Sanders, 1977; Jalali and Thareja, 1985) and can also induce biological 
suppression of soil-borne pathogens effectively (Jalali and Thareja, 1981). Although 
VA-mycorrhizal endophytes are associated symbiotically with most crop plants, little 
is known of their role in the utilization of less or unavailable sources of phosphorus 
for plant growth. The aim of the present study was to investigate the impact of 
VA-mycorrhizal inoculation on growth and development, and nutrient-contents 
(N, P and K) of cowpea {Vigna unguiculata) grown in nutrient-deficient soil. 

In all these studies, nutrient-deficient soil (collected from Rawalvas, Haryana) 
was used. Procedures adopted by Phillips and Hayman (1970) and Jalali and 
Domsch (1975) for root clearing and staining, and assessment of mycorhizal 
colonization respectively, were employed. 

VA-mycorrhizal inoculation induced significant increase in height of the plants 
as compared to uninoculated controls. Mycorrhizal infection resulted in significant 
increase in total dry matter production of root and shoot. VA-mycorrhizal 
endophyte developed extensively (53.78% colonization) in root system of cowpea. 

N, P and K content of plants also increased significantly in mycorrhizal 
inoculated plants as compared to control. Of these nutrients, the pronounced Increase 
was observed in the uptake of P. 

REFERENCES 

Jalali, B. L., Domsch, K. H. 1975. Effect of systemic fungitoxicants on the development of 
endomycorrhiza. In : Endomycorrhiza, Eds. F. E. Sanders, B. Mosse, P. B. Tinker, 
Acad. Press, London, pp. 525-530. 

Jalali, B. L., Thareja, M. L. 1981. Management of soil-borne plant pathogens by vesicular- 
arbuscular mycorrhizal model system. Indian Phytopath. 34 : 115-116. 

C 150 ] 



Jalali, B. L., Thareja, M. L. 1985. Plant growth response to vesicular-arbuscular mycorrhizal 
inoculation in soils incorporated with rock phosphate. Indian Phytopath. 38 : 306-310. 

Mosse, B. 1973. Advances in the study of vesicular-arbuscular mycorrhiza. Ann. Rev. Phytopath. 
11 : 171-196. 

Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing root and staining parasitic 
and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. 
Brit. Mycol. Soc. 55 : 158-161. 

Sanders, F. E., Tinker, P. B., Black, R. L., Palmerlary, R. H. 1977. The development of endomy- 
corrhizal root system. I. Spread of infection and growth-promoting effects with four 
species of vesicular-arbuscular endophyte. New Phytol. 78 : 257-268. 



\ 151 ] 



Vesicular-arbuscular (VA) mycorrhiza in presence of Rhizobium sp. 
enhances nodulation, N 3 fixation, N utilization of pigeon pea 

(Cajanus cajan) as assessed with a 15 N technique 

C. S. SINGH 

Microbiology Division 

Indian Agricultural Research Institute, New Delhi-1 10012 

Vesicular-arbuscular mycorrhizae (VAM) fungi are now known to enhance 
nutrient uptake, especially in P-deficient soil. However, N 2 fixation of various crops 
such as soybean, chickpea etc. has been reported to be enhanced in presence of VAM 
inoculation, as assessed by 15 N isotopes dilution technique (Barea et al, 1987; Subba 
Rao et al., 1986). Pigeon pea (C. cajan) forms very poor nodule with native Rhizobium 
sp. under field condition and life of the nodule is also very short, thus reflect on N 2 
fixation. Therefore it was essential to study the role of VAM fungi inoculation, in 
association with Rhizobium sp. on symbiotic process, especially on N 2 fixation, of this 
legume, using 15 N isotopes dilution technique under soil potted condition. 

Root colonization (%) of pigeon pea (C. cajan) was increased due to soil 
inoculation of G. fascjculatus (VAM). However, higher root colonization was recorded 
with combined inoculation of Rhizobium-\-\ AM than soil inoculated with VAM alone, 
at various levels of nitrogenous and phosphatic fertilization. Fertilization with 20 kg 
P 2 5 ha -1 brought perceptible increase in mycorrhizal infection in root over control. 
However, combination of nitrogen and phosphorus fertilizer (20 kg N ha -1 and 50 kg 
P 2 5 ha -1 ) in presence of VAM resulted in maximum mycorrhizal root infection. 

Improvement in nodulation was observed due to soil inoculation with VAM 
alone and it was scored more in presence of 20 kg N ha -1 and 50 kg P 2 5 ha -1 . The 
increase in nodulation with VAM, in presence ofNandP, was almost equivalent to 
the effects of seed inoculation with Rhizobium sp. alone. Another interesting obser- 
vation could be made from the result that incorporation of 20 kg N ha -1 did not 
influence nodule number. However, application of N and P (20 kg N ha -1 and 50 
kg P 2 5 ha -1 ) resulted in significant increase in nodulation over kg P 2 5 ha -1 
level, especially with dual inoculation of Rhizobium sp.+ VAM. Significant increase 
in nodule number was also recorded with Rhizobium sp. inoculation at all levels of N 
and P fertilization of soil. 

Grain and shoot yield of pigeon pea was significantly increased due to Rhizobium 
sp. and VAM inoculation, over uninoculated control, at all levels of N and f 

[152 ] • 



fertilization. The increase in grain and shoot due to VAM inoculaticn was almost 
equivalent to yield recorded with Rhizobium sp. inoculation alone and combined 
inoculation with the organisms significantly enhanced the yield (grain and shoot), 
especially in the presence of 20 kg N ha- 1 . The result also indicate that pigeon pea 
crop was more benefited due to P and N (50 kg P ha -1 and 20 kg N ha -1 ) application, 
as far as yield was concerned especially when the two endophytes are inoculated 
together. 

In this experiment no generalization can be made with the increase in % 
nitrogen of grain and shoot. However, total N yield in grain and shoot as calcula- 
ted on % N and total yield (grain and shoot, respectively) was recorded maximum 
with combined inoculation of Rhizobium sp. and VAM as compared to the increase 
brought due to inoculation of individual organism. The total N yield increase of 
grain and shoot tissue was more pronounced at P and N application (50 kg P 2 6 ha -1 
and 20 kg N ha- 1 , respectively). It was recorded more with VAM than Rhizobium sp. 
inoculation, even in presence of P and N fertilization. It is also worth to point out 
that total N yield was recorded higher in shoot portion of the plant than grain. 

In general % 15 N in the grain and shoot tissue of the plant was higher in 
absence of P and it was even more higher in the presence of Rhizobium sp.+ VAM 
inoculation. There was a higher amount of 15 N in grain and shoot tissue of VAM 
inoculated plant as compared to Rhizobium sp. treated plant. Percent 18 N atomic 
excess was estimated higher in straw than grain tissue. 

Fertilizer N uptake from soil solution to the tissues of grain and shoot was 
significantly higher with VAM inoculation and it was more with the combined 
inoculation of Rhizobium sp. + VAM, at both P levels. However, significant increase 
in the fertilizer N uptake was also recorded even at N and P application (20 kg N 
ha -1 and 50 kg P 2 O g ha- 1 ) with VAM inoculation, as compared to corresponding 
control. There was a higher uptake of fertilizer N a uptake in shoot than grain 
tissues. 

Utilization of applied N ( 1S NH,) 2 S0 4 was significantly increased with VAM 
inoculated plant. Results have also indicated that combined inoculation {Rhizobium sp. 
+VAM) effect on fertilizer utilization was recorded higher than the plant inoculated 
with individual endophytes. Application of P did not adversely effect the fertilizer 
utilization by pigeon pea crop. The utilization of fertilizer N was estimated higher 
in shoot than grain. 

In general biological N 2 fixed in grain and straw was higher at 50 kg P ha -1 
and 20 kg N ha -1 fertilizer application either due to inoculation of Rhizob ium sp., 
VAM and/or combination of Rhizobium sp. + VAM. Biologically fixed N ofC 
cajan (grain and shoot) was recorded more with VAM as compared to Rhizobium sp. 
inoculation treatment. However, it was estimated maximum in presence of two 

[ 153 •] 



endophytes (Rhizobium sp.+VAM). It is worth to mention here that fixed N 
(biologically) was recroded more in shoot than grain (as estimated by total N yield- 
total N assimilated in tissue from ("NHOjSO*). 

Nodulation and grain yield of pigeon pea (C. cajan) was significantly increased 
due to Rhizobium sp. and Glomus fasciculatus (VAM) inoculation especially at 50 kg 
P a 6 ha -1 application. VAM alone enhanced the nodulation of pigeon pea. Using 
15 N dilution technique ( 15 N H 4 ) S0 4 total N yield of the crop, utilization of soil 
nitrogen and biologically N 2 fixation was more with VAM inoculation, which 
was at par with Rhizobium sp. inoculation. N a fixed in grain and straw was higher 
due to combined effect of Rhizobium sp. and VAM, as compared to their individual 
effect. It was more pronounced in presence of 50 kg P 2 5 ha -1 and 20 kg N ha -1 in 
the form of super phosphate and ammonium sulphate respectively. 

Therefore it can be inferred that increase in total N yield of shoot and grain 
could be due to increase in translocation of soil nitrogen to plant mediated by VAM, 
resulted in improvement in nutrition of the crop plant. The higher amount of trans- 
location of soil N and P is positively correlated with the intensity of VAM root 
colonization and symbiotic parameters. Thus VAM has good potential in crop 
nutrition, in general. 

REFERENCES 

Barea, J. M„ Azcon-Aguilar, C, Azcon, R. 1987. Vesicular-arbuscular mycorrhiza improve both 

symbiotic N a fixation and N uptake from soil as assessed with a 1B N technique under 

field conditions. New Phytol. 106 : 717-725. 
Subba Rao, N. S., Tilak, K. V. B. R., Singh, C. S. 1986. Dual inoculation with Rhizobium sp. 

and Glomus fasciculatum enhances nodulation, yield and nitrogen fixation in chick pea 

(Cicer mietinum Linn). Plant and Soil 95 : 351-359. 



[ 154 ] 



Effect of interaction between Rhizobium and VA mycorrhizal fungi 

inoculation on the growth of groundnut applied with different levels 

of gypsum 

P. SANTHANAKRISHNAN AND G. OBLISAMI 

Department of Agrl. Microbilogy, Tamil Nadu Agricultural University 

Coimbatore-641 003 

The nutritional requirements of legumes are in no way different from other 
plants, except their potential for symbiotic assimilation of dinitorgen, creating special 
demands, notably for molybedenum, cobalt and also for phosphate, calcium and 
zinc. Any nutritional disorder may limit nitrogen fixation for the symbiotic system 
on the growth of plants (Munns and Mosse, 1980). 

It is well documented that groundnut is associated with VA-mycorrhizae 
(Graw and Rehme, 1977). It has been reported that VA-mycorrhizae help in 
increasing the absorption of nutrients such as calcium and zinc from soil (Copper 
and Tinker, 1978), In Tamil Nadu gypsum is recommended to get the increased 
yield of groundnut. There seems to be no information available on the effect of 
dual inoculation of Rhizobium and VA-mycorrhizae with different levels of gypsum 
on the growth oi groundnut. The objective of this study was to determine the levels of 
of gypsum for getting maximum benefit while using dual inoculation of Rhizobium 
and VA-mycorrhizal fungi for groundnut. The experiment consisted, of sixteen 
treatments (4 levels of gypsum x control; Rhizobium, VA-Mycorrhizae, Rhizobium+ 
VA-mycorrhizae) with three replications, Plant dry weight, VA-mycorrhizal coloni- 
zation, P content of plant and calcium content of plant were recorded at 30, 60 and 
90th days after sowing. 

In general, dual inoculation was found to be superior over individual 
inoculants or control at 30th and 90th day. Significant interactions were observed 
between gypsum levels and inoculants on 60th and 90th day so far as dry weight of 
plant was concerned. 

Colonization of root by VA-mycorrhizal fungi significantly increased due to 
inoculation of VAM fungi alone or combination of Rhizobium+VAM over uninol- 
culated control at three stages of growth. There was an increse in colonization of 
VA mycorrhizal fungi up to 150 kg/ha rate with a decrease in VA-mycorrhizal 
colonization with further increase up to 450 kg./ha of gypsum. There was gypsum 
levels and inoculants interaction on 60th and 90th day. 

[ 155 ] 



With regard to phosphorus content of plant, significant interactions were 
observed between the two variables at any sampling time. Dual inoculation of 
Rhizobium and VA-mycorrizal fungi was on par with individual inoculation of VAM 
fungi on increase of shoot and root P content of groundnut. 

So far as calcium content of plant was concerned, there was a large and highly 
significant response due to dual inoculation with 150 kg. /ha of gypsum level with 
no further response to 450 kg/ha. A significant interaction between inoculation 
and gypsum levels on shoot calcium content (30th day) and root calcium content 
(30th and 60th day) was observed. 

The present study brings out clearly that magnitude of increase of growth, 
VA-mycorrhizal colonization and nutrient content in groundnut plant were maximum 
due to dual inoculation as compared to individual inoculants at 150 kg/ha. P content 
of groundnut plant was maximum due to dual inoculation at 150 kg/ha. presumably 
due to the synergistic effect o both the symbionts. However, at 300 kg ha -1 or more 
there was a reduction in VA-mycorrhizal colonization due to VAM application with 
or without Rhizobium. Although information on the influence of gypsum on VAM 
colonization is scarce, a similar type of work employing calcium (a constituent of 
gypsum) indicated that higher concentration of calcium greatly inhibited colonization 
of Glomus mosseae (Elmes and Mosse, 1984). Such an apparent change in VAM 
colonization due to gypsum addition may be due to change in the soil pH (7.5 to 
8.6) caused by the addition of gypsum. The present study adds that dual 
inoculation help grundnut in a large way. 

REFERENCE 

Copper, K. M., Tinker, P. B. 1978. Translocation and transfer of nutrients in vesicular-arbuscular 

mycorrhiza. II uptake and translocation of phosphorus, zinc and sulphur. New Phytol. 

81 : 43-52. 
Elmes, R., Mosse, B. 1984. VA inoculation production. 11 Experiments with maize (Zea mays) 

and other hosts in nutrient film culture (NFT). Can. J. Bot. 62 : 1531-1536. 
Graw, D., Rehme, S. 1977. Vesicular-arbuscular mycorrhizae in the pegs of Arachis hypogaea. 

Z. Acker Planzenban. 145 : 75-78. 
Munns, D. N., Mosse, B. 1980. Mineral nutrition of legume crops. In : Advances in legume 

science, Eds. R. J. Summer field, A. H. Bunting, Proc. Intemat Legume Conf , Kew, 

pp. 115-125. 



[ 156 ] 



Yield and nutrient uptake by brinjal as influenced by Azospirillum 

brasilense and/or Glomus fasciculatum inoculations under graded 

phosphorus levels 

D. V. INDI, B. K. KONDE, P. V. WANI AND P. N. KALE 

D partment of Plant Pathology and Agricultural Microbiology, 

Mahatraa Phule Agricultural University, Rahuri-413 722 (M. S.), India 

VAM inoculations to vegetables have increased the yield through increased 
uptake of P and other nutrients particularly in low fertility soils (Ramachandra and 
Rai, 1987). Azospirillum brasilense inoculation has also improved the yield and 
nutrient uptake by vegetables (Patil et ah, 1989). Recently, the synergistic interac- 
tions of VAM fungi and Azospirillum improved the growth, yield and nutrient uptake 
in various crops (Subba Rao et al, 1985). However, the information on the effect of 
A. brasilense and or Glomus fasciculatum inoculations at various levels of applied 
phosphorus is scanty. A field experiment was, therefore, conducted on brinjal cv. 
Pragati on a P deficient soil (Olsen P=3.6 ppm; 75 chlamydospores 5(Hml soil) 
during the rainy season (June-December) of 1988 in a split plot design with four 
replications. The five P a 5 levels (0, 12.5, 25, 37.5 and 50 kg ha- 1 designated as P , P lf 
P 2 , P 3 and P 4 respectively) were the main treatments whereas the four inoculation treat- 
ments (control, A. brasilense, G. fasciculatum and A. brasilense +G. fasciculatum) 
served as the sub-treatments. The mycorrhizal seedlings were raised by inoculating the 
nursery bed (1.0x3.0 m) with 5 kg inoculum of G. fasciculatum (soil+sand (1:1) 
mixture; 415 chlamydospores 50" 1 ml). The non-mycorrhizal seedlings were obtained 
from the bed applied with equal quantity of uninfected mixture. For A. brasilense 
inoculation, the roots of 48 d old seedlings were dipped in the suspension of carrier- 
based inoculum (250g lit -1 water) for half an hour before transplanting to the field 
plots. Nitrogen (100 kg ha -1 ), phosphorus (as per main treatments) and potassium 
(50 kg ha -1 ) were applied through urea, single superphosphate and muriate of potash 
respectively. The total fruit yields per plot were recorded in nine pickings. Nitrogen 
and phosphorus content of fruits of the fifth picking were determined by Micro- 
KjeldahFs digestion and distillation and vanadomolybdate yellow colour method 
(Jackson, 1971). 

The results in general revealed that the yield and the uptake of N and P 
by the fruits differred significantly for the P 2 5 levels, inoculations and their 
interactions. The yield was significantly improved with an increase in dose of 
P 2 6 upto P 3 level. The yeeld at P 3 level (27.58 t ha- 1 ) was at par with that recorded 

[ 157 ] 



at P 4 level (27.80 t ha -1 ). The individual inoculations improved the yield significantly 
over the control but a synergistic efi'ect was noticed after coinoculation which 
recorded the highest yield (25.80 t ha- 1 ). The interaction P 3 level x dual inoculation 
registered the highest yield (30.21 t ha" _1 ) and was significantly superior to all other 
combinations. The N uptake by fruits at P 4 level was although the highest (61.07 kg 
ha -1 ), it was at par with that recorded by P 3 level (60.31 kg ha -1 ). Both the endo- 
symbionts significantly enhanced the N uptake over the control but were at par with 
each other. Combined inoculalion, however, registered the highest N uptake 
(60.14 kg ha -1 ). Amongst the interactions, dual inoculation at P 3 level registered 
the highest N uptake (71.81 kg ha -1 ) and was significantly superior to all other 
combinations barring dual inoculation at P 4 level (69.83 kg ha -1 ). The P 3 level 
recorded the highest P uptake (13.46 kg ha -1 ) by fruits and was significantly superior 
to all other P levels. The combined inoculation registered the highest P uptake 
(1 1.61 kg ha- 1 ) followed by G. fasciculatum (10.26 kg ha- 1 ) and A. brasilense (8.84 kg 
ha -1 ). The interaction P 3 level x dual inoculation recorded the highest P uptake 
(17.10 kg ha -1 ) and was significantly superior to all other combinations. 

Amongst the various P 2 O s levels, P 3 (75% of recommended dose) coupled 
with inoculation treatments recorded the almost equal fruit yield (27.58 t ha- 1 ), N 
uptake (60.31 kg ha -1 ) and a significantly higher P uptake (13.46 kg ha -1 ) to that 
recorded by P 4 level conjugated with inoculations. This may be attributed to the 
efficient VA fungal activity either alone or in combination with A. brasilense at 
moderate P level. The best mutualistic relations of VAM fungi with the plants have 
been observed at moderate P levels (Bethlenfalvay <?/ ah, 1983). Azospirillum brasilense 
singly could enhance the yield and the uptake of N and P as reported earlier (Palil 
et ah, 1989). Glomus fasciculatum inoculation also improved the yield and uptake 
of N and P (Ramachandra and Rai, 1987). However, their combination resulted in 
a synergistic interaction which recorded the significant improvement in the yield and 
uptake of N and P by the fuits (Subba Rao, 1985). Dual inoculation at P 3 level 
appeared to be the most superior interaction recording the highest yield and uptake 
of N and P followed by the dual inoculation at P 4 level. Best performance of dual 
inoculation of pearl millet with Azospirillum and Glomus at moderate P a 5 level has 
been reported. (Santhanakrishnan and oblisami, 1987). Similar results have also 
been obtained by coinoculation of brinjal with Azotobacter chroococcum and Glomus 
fasciculatum at 50% recommended phosphorus (Ramachandra and Rai, 1987). Thus, 
it could be concluded that 25% of the recommended phosphorus can be saved if 
dual inoculation is used for brinjal. 

REFERENCES 

Bethlenfalvay, G. J., Bayne, H. G., Pacovsky, R. S. 1983. Parasitic and mutualistic associations 
between a mycorrhizal fungus and soybeans : The effect of phosphorus on the host 
plant-endophyte interactions. Physiol. Plant. 57 : 543-548. 

[ 158 ] 



Jackson, M L 1971. Soil Chemical Analysis. Prentice Hall of India (Ltd.), New Delhi, India. 
Patil, R. B., Konde, B. K , Pawar, H. K„ Khade, K K 1989. Field studies on the effect of 

Azotobacter chroococcum and or Azospirillum brasilense inoculations under fertilizer N- 

levels on growth, yield and nitrogen fixation in ginger (Zinziber officinales Rose). Paper 

presented during the State level Seminar on 'Ginger Development' held at Nahan 

(Distt. • Sirmur), H. P., March -3. 
Ramachandra, G. S., Rai, P. V. 1987 Effect of Azotobacter chroococcum and Glomus fasciculatum 

on growth and yield of brinjal (Solarium melongena L.). Indian J. Microbiol. 

27 : 78-80 
Santhanakrishnan, P., Oblisami, G. 1987. Effect of dual inoculation of VA mycorrhizal fungi and 

Azospirillum on nursery raised pearl millet varieties, 'National Workshop on Mycorrhizae' 

held at J. N. U., New Delhi, March 13-15, pp. 45. 

Subba Rao, N. S., Tilak, K. V. B. R , Singh, C. S. 1985. Synergistic effect of vesicular-arbuscular 
mvcorrhizae and Azospirillum brasilense on the growth of barley in pots. Soil Biol. 
Biochem. 17: 119-121. 



[ 159 ] 



Mycorrhizal status of some desert plants and their physiological 
significance 

A. SHANKAR, J. MATHEW, NEERAJ, R. KAUR, R.S. MEHROTRA, AND A. VARMA 
Microbiology Unit, School of Life Sciences, J. N. U., New Delhi 

Vesicular arbuscular mycorrhizae (VAM) is world wide in angiosperms 
(McGee, 1986). VAM are involved in uptake of essential mineral nutrients and 
water (Mikola, 1987). The importance of VAM to agricultural crops has been well 
documented. Studies on sand dunes plants have indicated that VAM plays a signi- 
ficant role in the growth of desert plants (Bergen and Koske, 1984) and stablization 
of sand dunes. Even though agriculrural and forest lands have been extensively 
studied for mycorrhizae, there are only a few reports on the significance of VAM 
under extreme desert conditions. Singh and Varma (1981) have reported the 
occurrence and importance of VAM in the metabolic functions of Indian xerophytic 
plants. This study reports the mycorrhizal associations and their significance on 
plants growing under stress conditions from arid and semi-arid regions. 

Plant roots and rhizospheric soils were collected from five regions of Rajasthan 
(Jodhpur, Ossian, Balotra, Bhikomkor and Shergarh). Except Jodhpur, all were 
sand dunes areas. The root samples preserved in FAA were cleaned, stained and 
mounted in lactophenol for examination. The percentage of mycorrhizal infection 
was determined nonsystematically. The spores were recovered from soil (Varma 
et ah, 1981) and mounted in PVLand observed under compound microscope. The 
spores were identified following the Manual of Trappe (1982) and Schenck and Perez 
(1987). 

Twenty four plant species from arid regions cf Rajasthan belonging to eight 
families were examined. 

Amaranthus caudatus was the most mycorrhized host and Indigofera cordifolia 
did not possess any symbiosis. All spores belonging to cactii (Opuntia ficusindica, 0. 
vulgaris and several others) were mycorrhizal. 

Fourteen species of different VA mycorrhizal fungal spores were isolated from 
the rhizospheric soils. They were grouped in six genera : Endogone (2spp.), Gigaspora 
(2 spp.), Glomus (6 spp.), Sclerocystis (2 spp.), Scutellospora (1 sp.), Achylospora 
(1 sp.). Most dominant species was Glomus macrocarpum which was uniformly 
present in all the rhizosphere samples. Several spores were seen to be new as they 
did not resemble with any of the type species. The characteristics of chlamydos- 

[ 160 ] 



pores of Glomus fasciculatum were : spore size 52— 116.2 x 1 12.6— 118 /im, wall 
7.6 /im thick, 3 layered, outer layer 2 /im thick, hyaline to yellow, middle 5 /*m 
thick, yellow to brown and innermost very thin and membranous. Diameter of 
subtending hypha 12.6 fira. The Sporocarp of Sclerocystis sinuosa was brown, 
253 /*m in diameter. Peridia 12.2 /*m, tightly enclosing sporocarp comosed of thick 
walled sinuous hyphae. Chlamydospores 44.0—115.5x33.0—81.0 /*m, ovate, 
elliptical, fusiform elliptical, wall Oi chlamydospore brown, 1.3—4.9 /im thick. The 
Glomus macrocarpum spore was slightly longer than wide, light yellow to golden 
brown to brown, 143-165-177 /tm in diameter, wall 16.8 fim thick, double layered, 
outer spore wall wrinkled, attachment rarely seen. Spore number was maximum 
during winter season (1260/50g air dried soil) and remarkably declined in summer 
months. The pH of the soil samples obtained from the arid zones were alkaline and 
in general the spore counts were low as compared to semi-arid zones where pH was 
nearly neutral. This suggests that the growth and spore production is inhibited by 
alkaline pH. The moisture content varied between 2.5-9.5 per cent. 

The spore count was higher when moisture content was above 6 per cent. 
However, no definite correlation could be established between spore count and 
mycorrhizal root infection. For example roots of Aerva javanica had only 8.6 percent 
root infection with 1050 spores per 50 g rhizospheres soil whereas Amaranthus caudatus 
had 185 spores with 65.6 per cent infection. Invariably the rhizosphere soils from 
the cultivated field showed higher spore counts but the extent of root infection 
was relatively low. This could be ascribed due to either influence of nutrients in Hhe 
soil (Singh and Varma, 1981) or water logging or fungal specificity (Khan, 1974). 
Root sample of cactii showed mycelia and vesicles but no arbuscules, this is in 
confirmity with the earliar observation of Rose (1981) on a cactus species Pachycereus 
pringeli. 

REFERENCES 
Bergen, M., Koske, R. E. 1984. Trans. Brit. Mycol. Soc. 83 : 157-158. 
Khan, A. G. 1974. /. Gen. Microbiol. 81 : 7-14. 
McGee. P. 1986. /. Bot. 34 : 585-593. 
Mikola, P. 1987. Agnew Botanik 61 : 15-23. 
Rose, S. L. 1981. Can. J. Bot. 59 : 1956-1960, 

Schenck, N. C, Perez, Y. 1987. Manual for identification of VA mycorrhizal fungi, 2nd edition. 
Singh, K., Varma, A. K. 1981. Trans. Brit. Mycol. Soc. 77 : 655-658, 
Trappe, J. M. 1982. Pkytopat/tology 72 : 1102-1108. 
Varma, A. K., Singh, K., Lall, V. K., 1981. Current Microbiol. 6: 207-212. 



[ 161 3 



Distribution and intensity of native VAM in Maharashtra region 

V. PRABHAKARA RAO, S. E. PAWAR AND S. N. SINGH 
BAIF Development Research Foundation, Wagholi, Pune 

Three dimensional system of soil, VA mycorrhiza and plant, if properly 
managed may substantially improve the production potential of nutritionally deficient 
soils and help in conserving the costly fertilizers reserves. However, maximum 
benefit from the system may be achieved only when a full information regarding 
plant species, their specific nutritional requirement, their ability to extract 
the nutrients from the soil, nutrient status of the soil, potentiality of the VA- 
endomycorrhizae, including their ability of adaptation to a specific soil, climate and 
plant species is in hand. A part of our findings is included in the present paper, 
which reports the distribution of VAM in soils at and around Wagholi (Pune). 

Rhizosphere samples containing roots and soil were collected from different 
sites in polythene bags. The roots were cleared and stained bv the procedure of 
Phillips and Hayman (1970). The VAM propagules were recovered from soil by 
sieving and decanting (Gerdemann and Nicolson, 1963). Their population was 
recorded in terms of number per gram oven dry soil. 

All the plants studied, showed the presence of VA mycorrhizae, but the extent 
of colonization varied. A variety of spores were recovered from the rhizosphere 
soils. They mainly belonged to the genus Glomus, however, azygospores of Acaulos- 
pora or Gigaspora were also recovered but very rarely. The higher number of spores 
(15 spores/g soil) was recorded in cultivated soils than the non-cultivated soils 
(10 spores/g soil). 

The population of spores in the rhizosphere varied with the plant species as 
well as soils. The average population in the rhizosphere of plants from non- 
cultivated soil ranged from 5 to 10 spores/g dry soil, the lowest being in the 
rhizosphere of Dalbergia sisoo and highest in that of Prosopis juliflora. 

In the rhizosphere of plants from cultivated fields, the highest spore population 
was recorded from millets and forage crops (Gramineae) i. e. 15 and 12 spores/g dry 
soil respectively. In millets, lowest population (6 spores/g dry soil) was in the 
rhizosphere of Triticum aestivum, while the highest (15 spores/g dry soil) in that of 
Sorghum vulgare. In forage crops, the range of population was from 8 to 12 
spores/g dry soil with minimum in the rhizosphere of Panicum maximum and maxi- 
mum in that of Paspalum notatum. The population in the rhizosphere of pulses 

[ 162 ] 



ranged from 6 to 10 spores/g dry soil, the lowest being in the rhizosphere of Vigna 
synensis and highest in that of Vigna radiata. The spore population of vegetable 
plant ihizosphere soils ranged from 2 to 9 spores/g dry soil, the lowest being in the 
rhizosphere of Solatium melongena and highest in that of Allium cepa. In the 
rhizcsphere soils of cil seed crops, the spore population was more or less similar 
and was 1 1 spores/g dry soil. 

The VA mycorrhizal infection consisted of hyphal, vesicles and arbuscules. 
The percentage infection varied with the soils and plant species. The infection in the 
plants from non-cultivated fields ranged from 15 to 91%, lowest in D. sisoo and 
highest in P. juliflora. The range of infection in the plants from cultivated field was 
from to 99%, there was no infection in Solarium melongena and highest in Paspalum 
notatum. In millets the range of infection was 61-96%, the lowest being in Pennisetum 
typhoidium while highest in Sorghum vulgare. The range of infection in pulses varied 
from 36-85%, the lowest infection was in Vigna mungo, while highest in V. radiata. 
In vegetable crops the infetion ranged from 0-89%, no infection was found in 
Solanum melongena where as it was highest in Allium cepa. The oil seed crops 
Arachis hypogea and Helianthus annus exhibited 92 and 94% infection respectively. 

In the Present study rhizosphere soil samples were collected from two different 
soils. Their plants showed different range of spore population/root infection in 
different soils. This may be attributed to the differences in the phsico-chemical and 
biological, characteristics. In all the host plants studied Paspalum notatum showed the 
highest percentage of root infection and considerably high population of spores. 
This plant is selected as a host plant for studying further aspects in the mass 
production. 

REFERENCES 

Gerdemann, J. W., Nicolson, T. H. 1963. Traits. Brit. Mycol. Soc. 47 : 751. 
Phillips, J. M., Hayman, D S. 1970. Trans, Brit Mycol. Soc. 55 : 158. 



C 163 ] 



The occurrence of vesicular-arbuscular-mycorrhizal fungi in arable soils 
of Konkan region of Maharashtra 

SUNITA DALAL AND K. V. HIPPALGOANKAR 
Deportment of Botany, Institute of Science, 
15 Madam Cama Road, Bombay-400 032 

A survey was conducted to quantify spore density and to assess the relation 
between available phosphorus, total phosphorus, total nitrogen and spore count. 
Soil samples were collected from five places in the Konkan region of Maharashtra 
viz. Madban, Dhamnas Ganpatiphule, Chiplun, Sangameshwar and Khed in the 
first week of June 1989, where the crops grown are generally rice and ragi. The 
soils are mostly acidic in this region, the pH ranging from 5.01 to 5.77. Spore 
density ranged from 30 to 715 per 50 gms air dried soil. The wet sieving and 
decanting technique of Gerdmann and Nicolson (1963) was used for isolating the 
spores. Species of Glomus and Acaulospora dominated the soils with few other 
VAM genera. It is concluded from the survey that there exists no significant 
relationship between the available phosphorus and spore density in this region. 

REFERENCE 

Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted from 
soil by wet sieving and decanting method. Trans. Brit. Mycol. Soc. 46 : 235-244. 



t 164 ] 



Interaction between Rhizobium, mycorrhiza, nitrogen and phosphorus 
and their effect on growth and symbiotic behaviour of 

Leucaena leucocephala 

R. P. GUPTA AND V. PUNJ 

Department of Microbiology 

Punjab Agricultural University, Ludhiana, Punjab 

Symbiotic nitrogen fixation in legumes decreases under P-deficient soils 
(Mosse, et al, 1976). Under such conditions, application of VA mycorrhizal fungi 
capable of uptaking phosphorus away from the phosphorus depleted zones enhances 
symbiotic nitrogen fixation as has been seen in case of arhar and peas (Gupta et al, 
1987; Bhandal et al., 1989). However, very little information is available on the 
role of Rhizobium in association with VA mycorrhiza on the growth and symbiotic 
behaviour of L. leucocephala, which is known to be the best forest tree for its quick 
growth and multiple uses such as fuel, fodder etc. The present investigation deals 
with the study of interaction of Rhizobium isolates and VA mycorrhiza and their 
effect on growth and symbiotic behaviour of L. leucocephala in presence and absence 
of nitrogen and phosphorus fertilizers. 

Rhizobium strains used were isolated from noduJes of L. leucocephala grown 
in Ludhiana district. VA mycorrhizal fungus, Glomus fasciculatum grown on lentil 
roots in sterilized soil was used. 

Pot experiment was conducted under sterile conditions in two sets. In the first 
set, four surface-sterilized seeds treated with Rhizobium cultures (10 s c. f. u./g) were 
sown in pots containing different levels of nitrogen (CAN) and phosphorus 
(superphosphate) which were later thined to one plant per pot. In the second set of 
experiment, the pots were inoculated with VAM spore suspension (200 spores/pot) 
after 10 days of growth. 

Observations were made for plant height, plant dry weight, nodule number, 
nodule dry weight and nitrogenase activity (Hardy et al, 1968); and phosphorus 
(Jackson, 1983) and nitrogen (McKenzie and Wallace, 1954) concentrations in stem 
and leaves after 60 days of growth. 

Rhizobiun, nitrogen and phosphorus interaction was found significant for 
plant dry weight, nodule dry weight and nitrogenase activity both in absence and 
presence of mycorrhiza. The best combinations were found to be PxNj M + R 4 , 

t 165 ] 



P^o M + R B and P!Ni M + R 5 for plant dry weight, nodule dry weight and nitrogenase 
activity respectively. 

All the interactions, viz., Rhizobium, nitrogen and phosphorus, nitrogen and 
Rhizobium as well as Rhizobium and phosphorus significantly affected the accumulation 
of phosphorus and nitrogen in stem and leaves both in presence and absence 
of mycorrhiza. 

Relatively low values of all parameters at P level suggests the need of 
phosphorus application for the establishment of Leucaena plants. The improvement 
in ancillary characters and nitrogenase activity by mycorrhizal application suggests 
positive role of mycorrhiza in plant productivity. 

Phosphorus is a critical limiting factor in case of legumes, translocation of 
phosphorus by mycorrhiza not only improves the growth of host but also helps in 
nodulation and nitrogen fixation. 

Dual inoculation with Rhizobium and mycorrhizal fungi not only enhances 
the nutrient content in the above grand plant material but also seems to provide 
a well-balanced and regulated nutrient supply, consequently the biosynthetic processes 
taking place in these adequately established legume. Rhizobium mycorrhizal 
association can lead to better productivity of Leucaena leucocephala. 

REFERENCES 

Bhandal, B. K.. Gupta, R. P., Pandher, M.S. 1989. Synergistic effect of strain Hup+ of R. 

leguminosarum and VA mycorrhiza on symbiotic parameters of two cultivars of P. 

sativum. J Agrt Sciences (Accepted). 
Gupta, R. P., Khurana, A. S., Pandher, M.S. 1987. Effect of dual inoculation of Rhizobium 

andVAM on symbiotic characters of C.cajan. In: Proceedings of Seminar on 

Fertilizer Industry-Process, Problems and Prospectives held from 21-23 June, 1988 at 

BHU, Varanasi (India). 
Hardy, R.W.F., Holsten, R. D., Jackson, E. K., Burns, R, C. 1968. The acetylene-ethylene 

assay for nitrogen fixation, Laboratory and field evaluation. PI. Physiol. 43:1185-1207. 
Jackson, M. L. 1973. Soil chemical analysis. Prentice Hall, New Delhi. 
McKenzie, H. A., Wallace, H. A. 1954. The Kjeldahl determination of nitrogen. AM. J. Chem. 

17 : 55-79. 
Mosse, B., Powell, C. L., Hayman, D. S. 1976. Plant growth response to vesicular arbuscular 

mycorrhiza IX Interaction between VA mycorrhiza, rockphosphate and symbiotic 

nitrogen fixation. New Physiol. 76 : 331-342. 



[ 166 ] 



Vesicular-arbuscular mycorrhizal associations in Glycine max (L.) 

Merrill, improves the symbiotic nitrogen fixation under water 

stress 

K. P. RAVERKAR, A. DWIVEDI AND K. V. B. R. TILAK 

Division of Microbiology, Indian Agricultural Research Institute 

New Delhi-110 012 

Water is prerequisite for the growth of any plant. Plants growing in a natural 
environments are rarely free from water stress. Low availability of water exerts a 
controlling influence on crop distribution and productivity (Fischer and Turner, 
1978). Interaction between plant and bacteria determines the efficacy of symbiotic 
nitrogen fixation in leguminous plants and it can be affected by both the aerial and 
bslow ground environments. The moisture stress has detrimental effect on the 
process of nitrogen fixation. This effect has been well documented for numerous 
crop species (Sprent, 1971; Minchin and Pate, 1975). 

Under low moisture levels, water absorption capacity of roots might be 
enhanced by mycorrhizae. The first systematic examination of mycorrhizal influence 
on plant-water relations was conducted by Safir et al. (1972) on soybeen plants. 

The main aim of this research was to investigate the enhancement of growth 
and nitrogen fixation in response to dual infection of Glycine max and to study the 
effects of VA-mycorrhizal formation on nitrogen fixation and growth, in nodulated 
and non-nodulated soybean under water stress. 

In order to evaluate the effect of different VA-mycorrhizal fungi on biological 
nitrogen fixation in soybean (cv. Lee) root nodules under moisture stress, the system 
developed by Khanna-Chopra et al. (1984) was adopted with some modifications. 
Pots (30 x 30 cm.) were filled with sandy-loam soil (pH 8.2 and available P-3.2 kg 
ha -1 ) up to 18 cm. from the bottom, and 4 cm. layer of gravel (0.5-1.5 cm. in size) 
was provided above the soil. The portion above the gravel (8.0) cm.) was filled wiih 
sandy-loam soil. A plastic pipe of 3.0 cm. diameter with a plastic container 
(200 ml.) at top was kept vertically on the surface of gravel for providing water to 
the lower part of the pot by drip action. The set up ensured deficit in the soil zone 
containing nodules but maintaining adequate water supply to the root system. The 
assembly without plastic pipe and container were steam sterilized before use. 

Soil-sand mixture containing extramatrical chlamydospores and infected root 
segments of Cenchrus ciliaris, infected by either Glomus fasckulatum Thaxter Sensu 

[ 167 ] 



Gerd., G. mosseae Nicol. and Gerd. and Gigaspora margarita Becker and Hall, grown 
for 100 days served as the inoculum. The inoculum contained 200 chlamydospores 
per 100 g of inoculum. A thin layer of inoculum (200 ml) was placed 2-3 cm. below 
the soil surface in pots before sowing to obtain mycorrhizal plants. The control 
treatments received sterilized VAM fungal inoculum. The seeds of soybean (Glycine 
max, cv. Lee) were sown in the pots. Four plants were allowed to grow in each pot. 
The experiment was laidout in a randomized block design consisting five treatments 
and each was replicated thrice. A basal dose of nitrogen at the rate of 25 kg ha -1 and 
phosphorus at the rate of 50 kg P a O s ha -1 in the form of urea and super phosphate, 
respectively, were applied to each treatment. 

All the pots received uniform irrigation with 300 ml of water each in 
upper and lower soil zone for the first thirty-five days. Thereafter, the pots were 
divided into following three sets : 
Set Ii : 300 ml of water day -1 was given to the top soil and 300 ml of water day- 1 

was given through the container attached to the pipe, which served as 

irrigated control. 

Set J a : A total of 600 ml. of water (200 ml each thrice a day) was given to the lower 
soil soil zone through the pipe, which created stress in the upper zone. 

Set I 3 : Lower zone was watered with half the quantity provided to Set I 2 . 

Colonization of roots with VA-mycorrhizal fungi was detected by following 
the method of Phillips and Hayman (1970) with some modifications. The tertiary 
root segments taken in vials containing 8 per cent KOH were allowed to clear over- 
night at room temperature. After decanting the KGH solution, excess alkali was 
neutralized with 1 per cent HC1 and stained with trypan blue for 12 hrs. The per cent 
mycorrhizal colonization was determined by using the systematic slide method 
(Hayman, 1970). Nitrogenase activity in terms of ARA levels in intact root nodules 
was estimated following the method of Hardy et al. (1968). Plant biomass, after 
drying at 60^ till constant weight, was recorded. Observations for all the parameters 
were recorded at the early pod formation stage, 

Moisture stress in the upper zone of soil had detrimental effects which resulted 
in reduced number of nodules, dry weight of nodules, plant biomass and nitrogenase 
activity as compared to the plants grown under normal conditions. 

In the set I 3 , the maximum per cent of mycorrhizal colonization of 26.50 was 
observed in the plants inoculated with G. margarita-SB 113 together. The intensities 
of reduction in number of nodules, dry weight of nodules and nitrogenase activity, 
under water stress, varied due to inoculation with different VA-mycorrhizal fungi. 
The maximum per cent of reduction (147%) in the number of nodules occurred in 
the plants inoculated with SB 113 alone, whereas, in the presence of various VAM 
fungi along with bradyrhizobia it ranged between 41-59 per cent. Reduction in dry 

[ 168 ] 



weight of nodules of the plants grown in the set I a ranged between 7-65 per cent as 
compared to plants grown in Set Ij. Although minimum reduction (7%) was noticed 
in the plants receiving dual inoculum of G. mosseae and bradyrhizobia, the highest 
dry weight of nodules (335 mg plant" 1 ) was registered in the treatments receiving 
dual inoculum of G. margarita and bradyrhizobia. Average reduction in nitrogenase 
activity in nodules of the plants grown in set I 8 as compared to set Ii, ranged from 
8-29 per cent. In general, nitrogenase activity was improved significantly due to 
various VA-mycorrhizal fungi. In set 1 2 highest increase in nitrogenase activity was 
registered (185%) due to dual inoculation with G. margarita and bradyrhizobia over 
the inoculation with bradyrhizobia alone. 

In the nodules obtained from plants stressed in the upper zone, reduced 
nitrogenase activity was observed (Khann-Chopra et ah, 1984) in comparison 
to in nodules obtained from fully irrigated plants. Nitrogen fixation has been 
shown to be sensitive to reduction in soil water availability for numerous 
crops (Engin and Sprent, 1973; Minchin and Pate, 1975). Finn and Brun (1980) 
have suggested that water stress reduces nitrogen fixation by the inability of stressed 
leaves to supply photosynthates to nodules. Total plant biomass aJso responded 
significantly to the dual inoculation with VA-mycorrhizal fungi and bradyrhizobia 
under normal as well as stress conditions. 

Beneficial effects of VAM towards increasing various parameters including 
nitrogenase activity under water stress condition could be attributed to : 

i) Fungal hyphae extending out into the soil, accounting for the increased ability in 
water uptake / 

ii) The hyphae could enhance nutrient uptake, which in turn, could decrease the 
resistance to water transport with in the roots 

iii) The hyphae, which penetrate the root cortex to the endodermis could provide a 
low resistance pathway for water movement across the root (Safir et al., 1971). 

Nodular water probably flows through the root vascular tissue before entering 
the nodule (Sprent, 1972). So, mycorrhizal hyphae could enhance the flow of water 
to the nodule through the root vascular tissue, by tapping the water sources available 
outside the vicinity of rhizosphere and prevent the nodule from dessication. 

REFERENCES 

Engin, M., Sprent, J. I. 1973. Effects of water stress on growth and nitrogen fixing activity of 

Trifoliumrepens. New Phytol. 72 : 117-126. 
Finn, S.A., Brun, W.A. 1980. Water stress effects on CO a assimilation, photosynthate partitioning, 

stomatal resistance and nodule activity in soybean. Crop Set. 20 : 431-435. 
Fischer, R.A., Turner, N.C. 1978. Plant productivity in the arid end semi-arid zones. Ann Rev 

Plant physiol. 29 : 277-317. 

[ 169 ] 



Hardy, R.W.F., Holsten, R.D., Jackson, S.K., Burns, R.C. 1968 The acetelene-ethylene assay for 

N-fixation : Laboratory and field evaluation. Plant Physiol. 43 : 1185-1207. 
Hayman, D.S. 1970. Endogone spore numbers, in soil and vesicular-arbuscular mycorrhiza in 

wheat as influenced by season and soil treatment. Trans. Brit. Mycol. Soc. 54 : 53. 
Khanna-Chopra, R., Koundel, K.R., Sinha, S.K. 1984. Simple technique of studying water deficit 

effects on nitrogen fixation in nodules without influencing the whole plant. Plant Physiol. 

76 : 254-256. 
Minchin, F.R., Pate, J.S. 1975. Effects of water aeration and salt regime on nitrogen fixation in 

nodulated legumes definition of an optimum root environment. J. Exp. Bot. 26 : 60-69. 
Phillips, J.M., Hayman, D.S. 1970. Improved procedures for clearing roots and staining parasitic 

and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Brit. 

Mycol. Soc. 55 : 158-161. 
Safir, G.R., Boyer, J.S., Gerdemann, J.W. 1972. Nutrient status and mycorrhizal enhancement of 

water transport in soybean. Plant Physiol. 49 : 700-703. 
Sprent, J.I. 1971. Effects of water stress on nitrogen fixation in root nodules. Plant Soil. (Special 

Vol.): 225-228. 
Sprent, J.I. 1972. The effects of water stress oti nitrogen fixing root nodules IV. Effects of whole 

plants of Vtctafaba and Glycine max. New Phytol. 71 : 603-611. 



I 170 ] 



Effect of VAM on mulberry cultivation : New avenues of VAM 
application 

D. RAJAGOPAL AND KAISER JAMIL 
Indian Institute of Chemical Technology, Hyderabed-500007 

Mulberry is widely used for sericulture in India, as well as other silk producing 
countries of the world. The occurrence of vesicular arbuscular mycorrhiza (VAM) 
in mulberry is of great significance, as it is efficient in absorbing nutrients from soils 
and enhancing the root and shoot system for fixing phosphorus in phosphorus- 
deficient soils. It also increases the water absorbing capacity of the roots. 

VAM isolated from the roots of field collected Moms alba (LK a variety) were 
inoculated in sterile soil in which the susceptible sorghum seeds were planted. 
Sorghum has been reported to be a good host for the multiplication of VAM. 
Hence studies were undertaken to utilise the VAM rich bed for replantation of 
mulberry cuttings. 

Microscopic examinations of the roots revealed that these were heavily infested 
with VAM. Studies on the sprouting, growth rates in the root system and the 
multiplication of VAM will be discussed. This has great potential for dry land 
farming, where there is low soils and less nutrients. 



[ 171 ] 



Side-effects of pesticides on mycorrhizal system-an overview 

BUSHAN L. JALALI 

Department of Plant Pathology 

Haryana Agricultural University, Hisar-125004 

Conceptually, pesticides are tailored to react with living cells. Although these 
toxicants are directed against target pathogenic organisms, a good number of these 
biocides have deleterious influences on non-target organisms including symbiotic 
relationships involved in mycorrhizal model systems. While quantifying the impact 
of soil fungitoxicants on the growth and development of VA mycorrhiza in wheat, 
Jalali (1979) observed that soil application of four toxicants adversely affected the 
colonization of the mycorrhizal fungi in host roots, and such effects were most 
pronouced in PCNB-treated soil. The ability for increased phosphate uptake by 
mycorrhizal root was also lost when soils were treated with thiram orPCNB. 
Earlier, Jalali and Domsch (1975) observed that seed, as well as foliar applications, 
with conventional and systemic fungitoxicants restricted the development of mycorrhi- 
zal endophytes on host roots. They postulated that since foljarly-applied pesticides 
may not be translocated intact to the roots, the side effects on mycorrhizae may be 
brought about by changes in the spectrum of root exudates as a result of the stress 
exerted by the pesticides. In further tests the systemic fungicides triforine and tride- 
morph applied to the hast foliage changed the pattern of amino acid exudation 
(Jalali and Domsch, 1977). 

Formation of mycorrhiza in clover roots was prevented by soil drenches of 
benomyl and thiophenate methyl, and the spread of established infections was halted 
(Boatman et al., 1978). Immersion of fungal inoculum in suspensions of the fungi- 
cides reduced iafectivity. However, clover plants grown in benomyl-tfeated soil did 
not retain enough fungicide to affect the amount of infection after transplanting into 
benomyl-free soil. Similarly, while studying the effect of five fungicides on VA 
mycorrhizal symbiosis in onion grown in phosphate-deficient soils, Manjunath & 
Bagyaraj (1984) showed that except for captan, all other test fungicides applied even 
at lower concentrations reduced plant growth and phosphate uptake. 

The foliar application of the symplastic fungicide fosetyl-al at different concent- 
rations to mycorrhizal leek (Alium porrum) plants significantly increased colonization 
by Glomus intraradices, the number of intra-matrical vesicles and plant growth, 
compared to inoculated but untreated plants (Jabaji-Hare and Kendrik, 1987) and 
these effects did not diminish with time. The mechanism by which fosetyl-al produces 

[ 172 ] 



this effect seems to be related to its role in altering root exudation. This fungicide 
causes a significant increase in exudation of soluble sugar from mycorrhizal roots, 
especially during the first few days after treatment. 

Population dynamics of mycorrhiza fungi in arable fields are inversely affec- 
ted more by fungicides than by herbicides, nematicides and insecticides. These 
chemicals usually decrease mycorrhizal infection and spore numbers, similar to the 
effects of benomyl applications. Benomyl, which decomposes in soil to yield carben- 
dazim and butyl isocyanate, has been shown to reduce percentage mycorrhizal 
infection in root samples (Tommerup and Briggs, 1981). Benomyl suspensions are 
toxic to several mycorrhizal endophytes on direct immersion and when mixed with 
irradiated or infested soil. This probably offers positive indications that soil drenched 
with benomyl is toxic to external mycelium from established infections so that new 
roots remain uninfected. Ectomycorrhizal development by artificially-introduced 
Pisolithus tinctorius and naturally occurring fungi was significantly inhibited by three to 
four foliar applications with triadmefon applied with the initial objective of controlling 
fusiform rust on loblolly seedlings (Marx et ah, 1986). Basidiocarp production by 
ectomycorrhizal fungi in fungicide-treated plots was 3 to 10 times less than in the 
control. 

Several investigators have demonstrated that several commonly used herbicides 
drastically affect mycorrhizal fungi. However, Kelley and South (1980) observed that 
with few exceptions, herbicide concentration necessary to affect fungal growth were 
much higher than recommended doses. Furthermore, several herbicides are reported to 
stimulate growth of some ectomycorrhizal fungi in axenic cultures, usually at low 
concentrations. However, this response does not correlate with any specific group of 
toxicants. Chlorotoluron, under certain conditions, has resulted in increased spore 
populations of mycorrhizal fungi in soil, but mycorrhizal formation in hosts remains 
either unaffected or suppressed (Nemec and Tucker, 1983). Schwab et ah ( 1 982) 
postulated that mycorrhizal formation was promoted by a simazine-induced increase 
in the root exudation of sugars and amino acids. In nurseries, herbicides that tend 
to promote mycorrhizal diversity might be preferred under certain conditions, but in 
others it might be possible to control weeds with a toxicant that at the same time is 
able to promote growth of specific, inoculated mycorrhizal fungi. 

By and large, the systemic pesticides as a group appear more damaging to 
mycorrhizal symbiosis than non-systemic ones. Such toxicants affect spore germi- 
nation and ultimately colonization of the mycorrhizal endophyte within the host root 
system. Since translocation is primarily upwards, systemics would be more damaging 
to mycorrhizal fungi when applied as soil drenches. These findings indicate that 
investigations on the impact of a pesticide on mycorrhizal colonization should 
consider whether infection level attained under pesticide use will benefit the 
host. 

[ 173 ] 



REFERENCES 

Boatman, N., Paget, D., Hayman, D.T., Mosse, B. 1978. Effects of systemic fungicides on 
vesicular-arbuscular mycorrhizal infection and plant phosphate uptake. Trans. Brit. 
Mycol. Soc. 70 : 443-450. 

Jabaji-Hare, S H , Kendrik, W.B. 1987. Response of an endomycorrhizal fungus in Allium porrum 
L. to different concentrations of systemic fungicides, metalaxyl (Ridomil) and fosetyl-Al 
(Aliette). So/7 Biol. Biochem. 19 : 95-99. 

Jalali, B.L. 1979. Effects of soil fungitoxicants on the development of VA-mycorrhiza and phosphate 
uptake in wheat. In : Soil-Borne Plant Pathogens, Eds. B. Schippers, W. Gams, Academic 
Press, London, 11 : 525-530. 

Jalali, B.L., Domsch, KH. 1975. Effect of systemic fungitoxicants on the development of 
endotrophic mycorrhiza. In : Endomycorrhizae, Eds. F.E. Sanders, B. Mosse, P.B. Tinker, 
Academic Press, London, 11 : 619-626. 

Kelley, W.D., South, D.B. 1980. Effects of herbicides on 'in vitro' growth of mycorrhizae of pine 
[Pima spp.). WeedSci. 28 : 599-60.'. 

Manjunath, A., Bagyaraj, D.J. 1984. Effect of fungicides on mycorrhizal colonization and growth 
of onion. PI. Soil 80 : 147-150. 

Marx, D.H., Cordell, C.E., France, R.C. 1986. Effects of triadimefon on growth and ectomycorrhi- 
zal development of loblolly and slash pines in nurseries Phytopathology, 76 : 824-831. 

Nemec, S., Tucker, D. 1983. Effects of herbicides on endomycorrhizal fungi in Florida citrus 
[Citrus spp.) soils. WeedSci 31 : 427-431. 

Schwab, S.M., Johnson, E.L.V , Menge, J.A. 1982. Influence of simazine on formation of vesicular- 
arbuscular mycorrhizae in Chenopodium quinons. PL Soil. 69 : 283-28 I. 

Tommerup, I.C., Briggs, G.C. 1981. Influence of agricultural chemicals on germination of vesicular- 
arbuscular endophyte spores. Trans. Brit. Mycol. Soc 76 : 326-328. 



& 



i 174 ] 



Interaction between vesicular arbuscular mycorrhizal fungi and 
fungicides 

S. C. VYAS AND V. N. SHROFF 
J. N. Agricultural University, Campus Indore-452 001 

The importance of vesicular arbuscular mycorrhiza (VAM) fungi in plant 
growth, mineral nutrition and biological suppression of soil-borne plant pathogens 
has been demonstrated (Jalali, 1989). VAM are formed by Glomus species with roots 
of many cultivated crops (Gerdemann and Trappe, 1974). The use of fungicides for 
the control of some plant diseases is indispensible. The review examines some of the 
interactions between fungicides and VAM fungi. 

A. Interactions : 

Diverse groups of fungicides are primarily used to reduce soil and seed-borne 
pathogens invariably and their application, however, results in increase (Jabaji Hare 
and Kendrick, 1985) or no effect (Nemec, 1980) or in reduction or delaying VAM 
infection (Nesheim and Linn, 1969) but rarely eliminate them Menge, 1982). The 
subject has been reviewed recently (Vyas, 1988). The adverse effect of fungicides 
such as botran, PCNB, vapam, vorlex, mylon, lanstan in corn (Nesheim and Linn, 
1969), benomyl and thiophanate in clover, onion and strawberries (Clark, 1978), 
dichlofluanid, ethirimol, chloraniformethan, thiabendazole, triforine, and triademofon 
in wheat (Jalali and Domsch, 1975), benomyl in soybean and red clover (Bailly 
and Safir, 1978; Hale and Sanders, 1982) and dicloran, captan, benomyl, dazomet 
and PCNB in several crops (Menge, 1982; Nemec, 1980) have been observed. 

Application time has significant effect on the interaction of VAM and fungi- 
cides. Chlorothalonil, PCNB, benomyl, triademefon, chloroneb and iprodione 
reduced mycorrhizal development of bentgrass when applied 4 to 8 weeks after 
seeding and inoculated with G. fasciculatum. However, when they are applied 
16-20 weeks after seeding did not have adverse effect (Rhodes and Larson, 1981). 

Some fungicides such as pyroxychlor and prothiocarb, selective to oomycetes, 
appeared to have no effect on the VAM development (Poget et al., 1976; Stewart 
and Pfeger, 1977). Similarly captan at certain concentrations also had no significant 
effect on infection (Nemec, 1980). Chloroneb did not reduce VAM infection in 
bentgrass (Rhodes *nd Larson, 1981). 

[ 175 ] 



On the other hand, some fungicides increased root colonization and increased 
VAM activity and stimulated infection. An increase in VAM infection by soil 
application of captan in beans (Sutton and Sheppard, 1976) and dibromopropane 
in cotton (Bird et ah, 1974) was observed. Terrazolc significantly increased root 
colonization and spore production by G. fasciculatum in sorghum (Menge, 1982) 
while metalaxyl in maize (Groth and Martinson, 1983). Foliar application of 
systemic symplastic and anti-oomycetes fungicide, fosetyl-Al to leek plants signi- 
ficantly increased VAM colonization by Glomus sp. (Jabaji-Hare and Kendrick, 
1985). Earlier ro this Clark (1978) reprted 10 per cent increase in colonization 
by fosetyl-Al by Glomus microcarpum and two other unidentified Glomus spp. in 
lettuce by folair application. 

B. Mechanisms of fungitoxicity and stimulation : 

1. Fungitoxicity : Fungicides are per se toxic to the VAM spores and mycelium. 
Benomyl was toxic to VAM in a 3: 1 soil and sand mixture (Sutton and Sheppard, 
1976), although other group of zygomycetes are innocuous (Edgington et al, 
1974). 

2. Stimulatton : The increase in VAM activity in leek after folair application was 
due to root exudation of soluble sugars in mycorrhizal plant (M) in higher 
concetration than in nonmycorrhizal plants (NM); there was a significant 
increase in total lipid also in M roots. However, this increase was not observed 
in NM plants (Janaji-Hare and Kendrick, 1985). Fosetyl-Al directly or 
indirectly influenced the physiology of both host plant and VAM fungus. 

C. Effect of fungicides on phosphate accumulation by mycorrhiza : 

VAM fungi in plants have been demonstrated to increase plant growth by 
utilizing less available form of phosphorus in the soil. A 16-fold reduction of 32 P 
uptake was observed in 12 week-old M onions when PCNB was applied 48 hrs 
before application of labelled phosphorus (Gray and Gerdemann, 1969). Similar 
effects ware observed in maize and also in onion (Hirrel and Gerdemann, 1979). 
Soil drenches reduced phosphate uptake by benomyl and thiophanate in onion and 
strawberries (Clark, 1978) and PCNB and thiram at 100 ppm each in wheat (Jalali, 
1979). 

Studies on VAM at the root surface are of vital interest because of their 
potential biofertiJizer effects and biocontrol effects (Clark, 1978; Jalali, 1979). The 
repeated use of fungicides in farming systems merits careful consideration. It is 
suggested that the fungicides which posses narrow-spectrum, non-volatile, fungistatis 
and that are relatively nonspecific for VAM should be incorporated in the crop 
productivity schedule. 

[ 176 ) 



REFERENCES 

Bailey, J.E., Saflr, G.R. 1978. Effects of benomyl on soybean endomycorrhizae. Phytopathology 

68 : 1810-1812. 
Bird, G.W., Rich, J.R., Clover, S.V. 1974. Increased endomycorrhiza of cotton in soil treated with 

nematicides. Phytopathology 64 : 48-5 1 . 
Clark, C.A. 1978. Effect of pesticides on vesicular-arbuscular mycorrhizae, In : Rothamsed Exp. 

Sta. Res. Rep. for 1978 Part, i., pp. 236-237. 
Edgington, L.V., Khew, K.L., Barron, G.L. 1974. Fungitoxic spectrum of benzimidazole compounds. 

Phytopathology 61 : 42-44. 
Gerdemann, J.W. , Trappe, J.M. 1974. The endogonaceae in the pecific Northwest. Mycologia 

Memoirs 5 : 1-76. 
Gray, L.E., Gerdemann, J.W. 1969. Uptake of phosphorus-32 by vesicular-arbuscular mycorrhiza 

fungus. Plant Soil 30 : 415-422. 
Groth, D.E., Martinson, C.A. 1983. Increased endomycorrhizal infection of maize and soybean 

after soil treatment with metalaxyl. Plant Dis. 67 : 1377-1378. 
Hale, K.A., Sanders, F.E. 1982. Effect of benomyl on VAM infection of red clover and conseque- 
nces for phosphorus inflow. /. Plant Nutrition 5 : 1355-1367. 
Hirrel, M.C., Gerdemann, J.W. 1979. Enhanced transfer between onions infected with VAM fungus. 

NewPhytol. 83:731-738 
Jabaji-Hare, S.H., Kendrick, W.B. 1985. Effects of fosetyl-Al on root exudation and composition 

of extracts of mycorrhizal and non-mycorrhizal leek roots. Can. J. PI. Path. 7 : 118-126. 
Jalali, B.L. 1979. Effects of soil fungitoxicants on the development of VAM and phosphate uptake 
in wheat. In : Soil-borne Plant Pathogens, Eds. B. Shippers, W. Gam, London Academic 
press, pp. 525-530. 
Jalali, B.L. 1989. Interaction between VA-mycorrhiza and plant pathogens. Mycorrhizae News 

1 (2) : 1-2. 
Jalali, B.L., Domsch, K.M. 1975. Effect of systemic fungicides on the development of endotrophic 
mycorrhiza. In : Endomycorrhizae, Eds. F.E. Snader, B. Mosse, P.B. Tinker, Academic 
Press, New York, pp. 6J9-626. 
Menge, J. A. 1982. Effect of soil fumigants and fungicides on VA fungi. Phytopathology 72 ; 

1125-1132. 
Nemec, S. 1980. Effects of 11 fungicides on endomycorrhizal development in sour orange. Can. J. 

Bot. 58 : 522-526. 
Nesheim, O.N , Linn, M.B. 1969. Deleterious effects of certain fungitoxicants on the formation of 

mycorrhizae on corn root development. Phytopathology 59 : 297-300. 
Paget, D.K., Boatman, N.N., Mosse, B. 1976. Rothamsted Rep. for 1975. Part-1, pp. 230. 
Rhodes, L.H., Larsen, P.O. 1981. Effects of fungicides on mycorrhizal development of creeping 

bentgrass. Plant Dis 65 : 145-147. 
Stewart, F.L, Pfeger, E.L. 1977. Influence of fungicides on extent of Glomus species in association 

with field grown peas. Trans. Brit. Mycol. Soc. 69 : 318-319. 
Sutton, J.C., Sheppard, BR. 1976. Aggrigetion of sand dune soil by endomycorrhizal fungi. Can. 

J. Bot. 54 : 326-333. 
Vyas, S.C. 1988. Nontarget effects of agricultural fungicides. CRC Press, Florida, USA, 
pp. 272. 

[ 177 ] 



Interaction of dual inoculation of VA-mycorrhiza and RMzobium 
with pesticides treated chickpea plants 

B. L. JALALI, M. L. CHHABRA AND R. P. SINGH 

Department of Plant Pathology 

Haryana Agricultural University, Hisar-125004, India 

Several reviews have compiled information on various factors, including 
microorganisms, which affect parasitism of plant roots by vesicular-arbuscular (VA) 
mycorrhiza. Informations have also been generated on side-effects of pesticides on 
this microbial model system. However, data available on interaction of dual inocu- 
lation of VA-mycorrhizal endophyte and Rhizobium with pesticides on crop plants, 
are fragmentary. Inoculation of chickpea plants with VA-mycorrhiza + Rhizobium 
was found to have synergistic effect on nodulation, plant growth, dry matter product- 
ion, nitrogen fixation and phosphorus uptake (Jalali and Thareja, 1982). Several 
legume crops inoculated with VA-mycorrhizal fungi and Rhizobium usually had a 
beneficial effect on plant growth, nodulation and nitrogen assimilation (Bagyaraj et ah, 
1979; Gueyo et al., 1988). The effect of dual inoculation of VA-mycorrhiza and 
Rhizobium with captan on field beans revealed its adverse effect on plant growth and 
nitrogen fixation (Kuccey and Bonetti, 1988). Several other studies clearly revealed 
that an effective VA-mycorrhizal fungus and Rhizobium could contribute to the 
efficiency of such a system, especially in nutrient-deficient soils. 

In the present studies, interaction of dual inoculation of VA-mycorrhizal fungus 
(Glomus fasciculatum) and Rhizobium with pesticide-treated chickpea (Cicer arietinum) 
plants grown in nutrient-deficient soil were assessed. The test pesticides used were : 
bavistin and aldrin (as seed treatment) and basalin (as soil application). Inoculation 
with G. fasciculatum and Rhizobium sp. (strain no. Ca 181) were carried out after the 
chickpea seeds (cv. H 75-35) were treated with bavistin and aldrin. In case of soil 
application, basalin was thoroughly mixed with the test soil. Procedures adopted by 
Phillips and Hayman (1970) & Jalali and Domsch (1975) for root clearing and 
staining, and assessment of mycorrhizal infection respectively were employed. 

Among the pesticides used as seed treatment, aldrin had most inhibitory effect 
on dual application (G. fasciculatum-}- Rhizobium) followed by bavistin. These 
pesticides significantly altered the plant height, total dry matter production of root 
and shoot, number of nodules and pods/plant, population dynamics of mycorrhizal 
sporocarps, as well as grain weight, as compared to uninoculated and inoculated 
plants with either G. fasciculatum or Rhizobium. N, P and K contents were also 

[ 178 ] 



significantly reduced by the application of these pesticides as compared to controls. 
The soil application of basalin resulted in most inhibitory effect on mycorrhizal 
colonization, total dry matter production with all recorded parameters, as compared 
to other pesticidal applications. Most potent effect was, however, expressed in case 
of number of nodules/plant and nutrient uptake. 

Studies are in progress to quantify the biochemical nature of root exudates in 
mycorrhizal as well as non-mycorrhizal host plants under the influence of these pesti- 
cides. 

REFERENCES 

Bagyaraj, D.J., Manjunath, A., Patil, R.B. 1979 - Interaction between vesicular-arbuscular 

mycorrhiza and Rhizobium, and their effects on soybean in the field. New Phytol. 82 : 

141-145. 
Gueye, M., Diem, H.C., Dommergues, Y.R. 1988. Variation of N g fixation on N and P contents 

of mycorrhizal Vigna unguiculata in relation to the progressive development of extradical 

hyphae of Glomus mosseae. J. App. Micro. Biochem. 3 : 75-86. 
Jalali, B.L., Domsch, K.H. 1975. Effect of systemic fungitoxicants on the development of endomy- 

corrhiza. In : 'Endomycorrhizas' Eds. F.E. Sanders, B. Mosse, P.B. Tinker. Acad. Press, 

London, 11 : 524-530. 
Jalali, B.L., Thareja, M.L. 1982. Studies on the plant growth response to vesicular-arbuscular 

mycorrhiza. Haryana Agri. Univ. Deptt. Plant Pathol. ICAR Rep. pp. 31. 
Kuccey, R.M.N. , Bonetti, R. 1988. Effect of vesicular arbuscular mycorrhiza! fungi and captan on 

growth and nitrogen by Rhizobium inoculated field beans. Can. J. Soil Sci. 68 (1) : 

143-149. 
Phillips, J. M., Hayman, D.S. 1970. Improved procedures for clearing and staining parasitic and 

VA-mycorthizal fungi for rapid assessment of infection. Trans. Brit. Mycol Soc. 55 : 158. 



t 179 1 



Effects of fungicides on vesicular-arbuscular mycorrhizal association 
and plant growth response of citrus seedlings 

RAMA S SINGH, HARDIP SINGH AND O. S. SINGH 

Department of Plant Pathology 
Punjab Agricultural University, Ludhiana 

The use of agricultural chemicals is essential for crop production in present 
era. It is also apparent that various chemicals used in plant protection affect non- 
target organisms for which these are not formulated and ultimately alter the 
microbial balance in a particular environment (Nemec, 1980). The vesicular- 
arbuscular (VA) mycorrhizal fungi are cosmopolitan in nature and occur with most of 
plant, species (Gerdemann, 1968; Harley and Smith, 1983; Hayman, 1982). Its 
population is also affected by the application of pesticides (Trappe et ah, 1984). The 
intensity of effect may vary with specific combination of host and symbiont. To 
grow healthy citrus seedling in nursery, different types of fungicides are used as soil 
or seed treatments. Hence, the experiments were conducted to observe the effect of 
various fungicides on VA mycorrhizal fungi in relation to rough lemon seedlings. 

The effects of soil treatment with ten fungicides, i. e. Bavistin (0.1%), Blitox 
(0.2%), Brassicol (0.25%), Captaf (0.2%), Captafol (0.2%), Copper sulphate (0.2%), 
Emisan (0.1%), Mancozeb (0.25%), Sulfex (0.25%) and Vitavax (0.15%) were 
noted on root colonization and spore population of VA mycorrhizal fungus in 
rhizosphere soil of rough lemon seedlings. 

The treatment of three fungicides, Mancozeb, Sulfex and Vitavax significantly 
reduced the root colonization and spore population. The minimum colonization, 
50.4% was observed in Mancozeb treated soil followed by 52.6% in Sulfex and 
52.8% in Vitavax against 76.2% in control. The numer of spores were also less in 
soil treated with these fungicides. There were 362, 370 and 379 spores/50 g. soil in 
Mancozeb, Vitavax and Sulfex treated soil respectively as compared to 501 spores/50g 
untreated soil. Other fungicides also suppressed the colonization and spores popu- 
lation of VA mycorrhizal fungi upto some extent, but the differences were non- 
significant. There were 60.2, 60.7, 65.7, 70.1,60.4, 59.6 and 58.3% mycorrhizal 
colonization and 420, 452, 475, 498, 441, 428 and 426 spores/50 g of soil treated 
with Bavistin, Blitox, Brassicol, Captaf, Captafol, Copper sulphate and Emisan 
respectively. 

The fungicides affect the establishment of mycorrhizae which ultimately 
influenced the root, shoot growth, number of leaves and their dry matter in rough 

[ 180 ] 



lemon seedlings. On average, the root length 8.2, 8.1 and 7.9 cm; the shoot length 

7.1, 6.9 and 7.4 cm along with 16, 14 and 15 number of leaves were recorded in 
seedlings grown in Mancozeb, Vitavax and Sulfex treated soil respectively as 
compared to 18.7 cm root, 17.8 cm shoot length and 29 leaves per mycorrhizal plant 
in non-fungicidal treated soil. Similarly, 12.9, 13.2, 13.6, 15, 12.9, 12.7 and 13 cm 
root length; 11.3, 14.3, 11.5, 14.7, 12.8, 11.4 and 11.2 cm shoot length as well as 22, 
25, 24, 28, 22, 23 and 25 number of leaves were observed per plant in Bavistin, 
Blitox, Brassicol, Captaf, Captafol, Copper sulphate and Emisan treated soil 
respectively. 

Dry matter of various plant parts of rough lemon seedling was affected due to 
imbalance of mycorrhizal colonization. It was significantly reduced in the seedlings 
grown in soil treated with three fungicides i.e. Mancozeb, Sulfex and Vitavax. On 
average, 0.6, 0.9 and 0.7 g dry weight of root, 0.7, 0.8 and 0.9 g dry weight of shoot 
as well as 0.9, 1.0 and 1.1 g dry weight of leaves per seedling were observed in 
Mancozeb, Vitavax and Sulfex treated soil respectively. However, the dry weights of 
root, shoot and leaves of mycorrhizal seedlings grown in untreated soil were 1.9, 2.1 
and 2.9 g respectively. The difference in dry matter production of the seedlings 
grown in soil treated with other fungicides were non-significant. The 1.3, 1.5, 1.7, 

1.2, 1.2, 1.6 and 1.6 g dry matter of root; 1.7, 1.9, 2.0, 1.8, 1.6, 1.4 and 1.3 g dry 
matter of shoot and 2.2, 2.5, 2.7, 2. 1, 2.1, 2.0 and 2.2 g dry matter of leaves/seedling 
were observed in Bavistin, Blitox, Brassicol, Captaf, Captafol, Copper sulphate and 
Emisan treated soil respectively. 

It was concluded that out of ten fungicides tested, Manozeb, Sulfex and 
Vitavax significantly reduced spore population and VA mycorrhizal colonization of 
rough lemon seedling which resulted in decrease in root, shoot growth, number of 
leaves and their respective dry matter. 

REFERENCES 

Gerdemann, J. W. 1968. Vesicular-arbuscular mycorrhizae and plant growth. Ann. Rev. 

Phytopath. 6 : 397-418. 
Harley, J. L., Smith, S. E. 1983. Mycorrhizal symbiosis. Academic Press London, N. Y. 
Hayman, D. S. 1982. Influence of soil and fertility on activity and survial of vesicular-arbuscular 

mycorrhizal fungi. Phytopathology 72 : 1119-1125. 
Nemec, S. 1980. Effects of fungicides on endomycorrhizal development in sour orange. Can. J. 

Bot. 58 : 522-526. 
Trappe, J. M., Molina, R , Castellorno, M. 1984. Reactions of mycorrhizal fungi and mycorrhiza 

formation to pesticides. Ann. Rev. Phytopath. 11 : 331-359. 



[ 181 ] 



Effect of methyl isocyanate on vesicular arbuscular mycorrhizal fungi 

V. MOHANKUMAR AND C. B. NIRMALA 
Centre for Advanced Study in Botany, University of Madras, Madras-600026 

Mycorrhizal fungi are cosmopolitan and are associated with the roots of most 
crops, helping in improved mineral nutrition. The use of fungicides and fumigants 
to control soil-borne pathogens is a common practice. Recently, concern has develo- 
ped among agriculturists about the effects of pesticide usage upon vesicular arbuscular 
mycorrhizal (VAM) fungi. The biocidal fumigants such as mylone, vapam and 
vorlex all decompose into methyl isocyanate (MIC), which for these fumigants is the 
active fungicidal compound in soil. MIC released into the soil consistently reduces 
mycorrhizal infection, both in the field and in the green house (Menge, 1982). Many 
of the observations of pesticides upon mycorrhizal fungi have taken place in the field 
and no attempt has been made to identify the fungal symbiont involved. In this 
study, methyl isocyanate, a basic ingredient in the production of various pesticides 
was tested for activity against Glomus fasciculatum. 

Fresh G. fasciculatum inocula from onion plant rhizospberes were used to 
evaluate their survival at various concentrations of MIC and their subsequent infection 
in onion plants. Each of the soil inocula contained 560 surface sterlized spores per 
lOOg sterilized soil and was used as inoculum for each of the pots containing sterilized 
soil, after exposing to 500, 1000 and 2500 ppm of MIC. Onion bulbs were planted 
in the pots and suitable controls were maintained. Mean plant dry matter produc- 
tion and infection data were recorded every 5 days for 45 days. 

Mycorrhizal plants showed a good phytomass production than non-mycorrhi- 
zal plants. Dry weight of plants grown ir soil with inocula exposed to 500 ppm and 
1000 ppm was lesser than the inoculated check, but was higher than the ones 
inoculated with 2500 ppm treated soil inoculum. Mycorrhizal control plants showed 
57 to 90% infection between 15 to 45 days. From 35 days onwards, 500 ppm 
treated soil showed mycorrhizal activity and the rate of infection was 45 per cent at 
45 days. Onion plants grown in 500 and 1000 ppm treated soil developed infection 
only after 30 days, but in the plants with 2500ppm treated soil infection was observed 
only on the 45th day, which was 3 per cent and purely hyphal. 

These tests showed that VAM has a range of sensitivity to the different 
concentrations of MIC. Differences were reflected in plant growth and extent of 
infection. The negative effect of MIC on VAM fungal population indirectly 

[ 182 ] 



suppressed the plant growth. Inoculum treated with 500 ppm of MIC did not alter 
much of the growth metabolism of onion. But 1000 and 2500 ppm of MIC 
proved to be toxic to VAM fungi, by reducing the plant growth. These results 
coincided with the studies on the effect of carbamate pesticides on plants. Nesheim 
and Linn (1969) noted reduced infection in corn fumigated withvapam. In citrus 
also vapam reduced VA infection significantly (Timmer and Leyden, 1978). Very 
poor infection was noted in corn and citrus roots due to the application of vorlex 
(Nesheim and Linn, 1969; Schenck and Tucker, 1974) and in corn and bean by the 
application of mylone (Nesheim and Linn, 1969; McEven et al, 1973). Sodium 
azide which is used in the preparation of MIC significantly reduced vesicle formation 
in citrus seedlings when used at a rate of 98% at 28, 84 and 147 kg/ha (Nemec and 
O'Bannon, 1979). Clearly, the composition of MIC in different pesticides must be 
standardized for the field applications. Results from such studies may predict the 
limits for field use of these chemicals in pest management programs. 

REFERENCES 

McEven, J., Salt, G. A., Horhby, D. 1973. The effects of dazomet and fertilizer nitrogen on 

field beans (Vicia faba L.). J. Agric. Sci. 80 : 105-110. 
Menge, J- A. 1982. Effect of soil fumigants and fungicides on vesicular-arbuscular fungi. 

Phytopathology 72 : 1125-113-'. 
Nemec, S., O'Bannon, J.H. 1979. Response of Citrus aurantium to Glomus etunicatus and G. mosseoe 

after soil treatment with selected fumigants. Plant Soil S3 : 351-359. 
Nesheim, O.N., Linn, M.B. 1969. Deleterious effect of certain fungitoxicants in the formation of 

mycorrhizae on corn by Endogone fasciculata and corn root development. Phytopathology 

59 : 297-300. 
Schenck, N.C., Tucker, D.P.H. 1974. Endomycorrhizal fungi and the development of citrus seedlings 

in Florida fumigated soils. J. Am. Soc. Hortic. Sci. 99 : 284-287. 
Timmer, L.W., Leydon, 1978. Relationship of seedbed fertilization and fumigation to infection of 

sour orange seedlings by mycorrhizal fungi and Phytophthora parasitica. J. Am. Soc. 

Hortic. Sci. 103 : 537-541. 



t 183 ] 



Effect of dichlone on Nostoc and VAM 

S. L. GUPTA 

Microbiology Unit, Botanical Survey of India 

Howrah-711 103, India 

A very complex relationship exists amongst plants, microbes and soil due to 
which many microbial activities governing relationship between plants and microbes 
are not fully explored. On one hand, the micropopulation present in the soil exert 
a decisive influence on the physiological activities of the plants (Subba Rao, 1977) 
and on the other, plants also supply their nutrients in the form of residues and 
excretions and affect them either on the root surface or in the vicinity of the roots. 
Many soil microflora such as fungi and algae show well known examples of symbiosis. 
Symbiosis involving cyanophycean microflora is of wide spread occurrence just like 
symbiotic mycorrhizal association between roots of higher plants and fungi. 

Although fungicides are normally used to control plant pathogens, their major 
portion is deposited on the surface of soil and might affect adversely the cyanobacterial 
and mycorrhizal species. Herein a preliminary attempt has been made to study the 
effect of fungicide dichlone (2,3-dichloro 1,4 naphthoquinone) on the survival of 
mycorrihza and cyanobacterium Nostoc sp. 

Both VAM (mostly Glomus sp.) and Nostoc sp. were isolated from garden soil. 
Survival was monitored on agar plates following application of graded concentrations 
of dichlone (ranges from 0.1 to 5.0 ppm). 

Being a fungicide, dichlone (commonly marketed as Phygon XL) is having 
limited application in controlling algal blooms (Owens and Novotny, 1958) in 
comparison to other algicides. Comparison of sensitivities of the cyanobacterium 
Nostoc sp. and VAM to dichlone revealed that VAM is found to be more resistant 
than to Nostoc. Concentrations above 2.5 ppm were effective against VAM (50% 
survival at 3.0 ppm) whereas concentrations as low as 0.5 ppm were effective against 
Nostoc (50% survival at 0.25 ppm)- In a previous study it was observed that 
among cyanobacteria, filamentous forms were more resistant in comparison to 
unicelluar forms and cyanobacterium Anabaena cylindrica was more resistant 
(Kashyap and Gupta, 1981) among filamentous forms. It was observed that dichlone 
alterd phycocyanin concentration earlier than other pigments leading to assumption 
that nitrogen fixation process might be impaired in the presence of dichlone, resulting 

{ 184 ] 



in the increased sensitivity of Nostoc in comparison to VAM as the latter do not 
contain phycocyanin. Further, the differential sensitivities due to different cellwall 
structure cannot be ruled out also. 

REFERENCES 

Kashyap, A. K.. Gupta, S. L. 1981. Effects of dichlone on growth, macromolecular synthesis and 
photosynthetic pigments in blue-green algae. Acta. Bot. Indica 9: 265-271. 

Owens, R. G., Novotny, H. M. 1958. Mechanism of action of the fungicide dichlone. Contrib. 
Boyce Thompson Inst. 19 : 463-482. 

Subba Rao, N. S. 1977. Soil microorganisms and plant growth. Oxford & IBR Publishing Co., 
New Delhi. 



t 185 ] 



Pesticides-mycorrhiza interactions on the growth and development 
of pigeonpea (Cajanus cajan) 

R. P. SINGH, M. L. CHHABRA AND B. L. JALALI 

Department of Plant Pathology 

Haryana Agricultural University, Hisar-125004 

Though diverse groups of pesticides are widely used for the control of weeds, 
nematodes, insects and diseases in plants, many a times the application of these 
pesticides result in indiscriminate killing of non-pathogenic/beneficial microorganisms 
(Domsch, 1964). It has now been well demonstrated that vesicular-arbuscular (V-A) 
mycorrhizal associations can greatly increase the growth of host plants, particularly 
when the available soil phosphorus is a limiting factor (Mosse, 1973). However, 
pesticides commonly ussd in farming systems may exert adverse influence on the 
symbiotic relationship between plant roots and the fungal endophyte. The inhibitory 
effects of fungitoxicants applied as seed as well as soil treatments on the development 
of V-A mycorrhiza and phosphate transport in wheat have been demonstrated (Jalali 
and Domsch, 1975; Jalali, 1979). The present study was undertaken with a view to 
quantify the impact of some commonly used pesticides on the colonization of V-A 
mycorrhiza, host growth as well as N, P and K uptake in pigeon pea (Cajanus 
cajan). 

The pigeonpea seeds (cv. Manak) were sown in pots (24 cm) containing 
nutrient-deficient sterilized soil (15 lb. psi for 2 h.). Bavistin, thiram and aldrin 
were used as soil as well as seed dressing; vitavax and captafol as seed treatment; and 
BHC, heptachlor, furadan and phorate as soil applications. The observations were 
recorded for dry matter production, plant height, N, P and K content of plants and 
mycorrhizal colonization of plant roots at different growth stages of the host plant. 
Mycorrhizal colonization was recorded by grading (grade 0-4) mycorrhizal 
infection along each root segment (Jalali and Domsch, 1975). N, P and K content 
of the plants were determined by the standard methods followed by Jackson 
(1958). 

Among the five pesticides used as seed treatment, thiram had most inhibitory 
effect on mycorrhizal colonization while captafol reduced total dry matter production 
drastically. Nutrient uptake was significantly reduced by the application of these 
pesticides as compared to untreated control. P-uptake was appreciably suppressed 
as compared to N and K. 

C 186 ] 



Of the soil pesticides, basalin had the most inhibitory effect on mycorrhizal 
colonization, plant height, total dry matter production and nutrient uptake followed 
by thiram and bavistin. Heptachlor had the least effect on various growth parame- 
ters followed by furadan and phorate. 

These observations clearly indicate that VA-mycorrhizal infection is considera- 
bly inhibited by the application of different pesticides. Of the test pesticides evaluated, 
the most drastic effects were observed with basalin, bavistin, captafol and thiram 
applications, which interfered, in varying degress with the growth and nutrient uptake 
of the plants. These results have some practical significance, since any interference 
with mycorrhizal development may ultimately have a depressive effect on plant 
growth and development. Therefore, the repeated use of pesticides in normal far- 
ming practices need careful consideration in our future plant protection strategies. 

REFERFNCES 
Domsch, K. H. 1964. Soil fungicides. Ann. Rev. Phytopathol. 2 : 293-320. 
Jackson, M. L. 1958. Soil Chemical Analysis, Prentice Hall, New Delhi. 
Jalali, B. L., Domsch, K. H. 1975. Effect of systemic fungitoxicants on the development of 

endotrophic mycorrhiza. In : Endomycorrhizas, Eds. F. E. Sanders, B. Mosse, P. B. 

Tinker, Academic Press, London, pp. 619-626. 
Jalali, B. L. 1979. Effects of soil fungitoxicants on the development of VA mycorrhiza and 

phosphate uptake in wheat. In : Soil Borne Plant Pathogens, Eds. B. Schippers, W. 

Gams, Academic Press, London, pp. 525-530: 
Mosse, B. 1973. Advances in the study of vesicular-arbuscular mycorrhiza. Ann. Rev. 

Phytopathol, 11 : 171-196. 



t 187 ] 



Effect of fungicides on mycorrhizal and rhizobial development in 
soybean 

S. C. WAS, ADITYA WAS, K. C. MAHAJAN AND V. N. SHROFF 
J. N. Agricultural University, Indore 

Soybean (Glycine max L.) requires adequate phosphorus supply for nodule 
production and nitrogen fixation (Van Schreven, 1958). Vesicular-arbuscular 
(VAM) fungi are known to improve plant phosphorus nutrition particularly in low P 
soils and other immobile elements. Inoculation of soybean with VAM and rhizobium 
in some soils was found to have synergistic beneficial effect on nodulation, nitrogen 
fixation and soybean growth (Carling et al, 1978). Soybean suffers from several 
seedborne pathogens which reduce plant stand in the field and thus result in reduction 
of grain yields. In order to control seedborne pathogens seed treatment with fungi- 
cides has been invariably carried out with fungicides like thiram, captan and 
carbendazim (Vyas, 1984). There is considerable evidence that the fungicide affects 
development of VAM fungi (Vyas, 1988). Hence, the present investigation was 
carried out to investigate the interactions of mycorrhizae, rhizobia and fungicides on 
the development of mycorrizal infection and colonization, nodulation and plant 
growth which is vital for rational use of fungicides in plant disease control without 
adversely affecting growth promoting mycorrhizal and rhizobial associations. 

The result of the present investigation indicate that the soil had a low level of 
indigenous VAM. Inoculation with Glomus spp. increased the percentage of 
mycorrhizal infection and colonization of roots of soybean plants and number of 
chlamydospores in the soil. The results further indicate that the inoculation of 
soybean with Rhizobium japonicum significantly increased number of nodule per plant 
and their weight and also plant dry weight. Similarly Glomus spp. also increased 
plant dry weight. The results also indicate that dual inoculation with Rhizobium and 
VAM increased mycorrhizal colonization and chlamydospores number.nodule number 
and their weight and plant dry matter weight. This response in likely due to impro- 
vement in nutrient balance of the host plant, especially nitrogen, phosphorus, zinc 
and coppar supply by VAM inoculation which results in enhanced nitrogen fixation 
(Carling et al, 1978). Seed treatment with thiram (0.3%) or carbendazim (0.15%) 
had no adverse effects on the dual inoculation with mycorrhizal and rhizobial as 
well as their various benefial effects to the plants. Similar effects were also 
reported by Groth and Martinson (1983). Kumar and Jayaraman (1987) observed 
abverse effects of carbendazim, thiram and captafol seed treatment with mycorrhizal 

[ 188 ] 



inoculation but this effect was nullified in the presence of fertilizers and farm yard 
manure. This and other interactions with agronomic practices need experimentations 
to elucidate the complexcity. 

It is concluded from this study that seed treatment with carbendazim (0.15%) 
and thiram had no adverse effects on the nodulation and mycorrhizal colonization in 
soybean cultivar, JS-72-44. 

REFERENCE 

Carling, D.E., Richie, W.G , Brown, M.E., Johnson, D.R. 1978. Effects of vesiculai-arbuscular 

mycorrhizal fungi on nitrate reductase and nitrogenase activities in nodulating and 

nonnodula ting soybean. Phytopathology 68 : 1590-1596. 
Groth, D.E., Martinson, C.A. 1983. Increased endomycorrhizal infection of maize and soybeans 

after soil treatment with metalaxyl. Plant Dis. 67 : 1377-1378. 
Kumar, Dinesh, Jayaraman, Jayshree. 1987. Influence of fungicides and fertilizer amendments on 

mycorrhizal associations in Vtgna mungo (L.) Hepper. Mycorrhizal Round Table. Proc. 

Natl. Workshop held at J. N. University, New Delhi, pp. 488-504. 
Van Schreven, D.A. 1958. Some factors in the fixation of nitrogen by the legume. In : Nutrition of 

the legumes, Ed. H.G. Hallsworth, Butterworth, London, pp. 137-163. 
Vyas, S.C. 1984. Systemic fungicides. Tata McGraw Hill Publishing Co. New Delhi, pp. 360. 
Vyas, S.C. 1988. Nontarget effects of agricultural fungicides. CRC Press, Florida, USA, pp. 272. 



Effect of insecticides on wheat crop inoculated with phosphate 
solubilizing bacteria (PSB) and VAM fungi 

A. C. GAUR AND J. P; S. RANA 

Division of Microbiology 

Indian Agricultural Research Institute, New Delhi-110012, India 

The effect of pesticides such as phorate and carbofuran applied to soil at 
recommended field dosage was studied on wheat crop. The seeds were inoculated 
with PSB (Pseudomonas striata) and soil was inoculated with Glomus fasciculatum. 
Simple application of these biocides slightly improved the growth, grain and 
straw yields. Seed treatment with PSB improved the growth and yield of the crop 
appreciably. Phorate slightly reduced the growth and yields but carbofuran 
application was compatible with PSB treatment. VAM application improved the 
yield of the crop over the control but was not better than PSB. The use of the 
insecticides did not inhibit the growth of the plant over the VAM inoculated 
treatment. The dual inoculation of PSB and VAM augmented the growth and 
yields of the crop and the biocides were compatible with the dual inoculation system. 

The same treatments were repeated in soil amended with superphosphate at 
60 kg ha" 1 . The yields were improved due to use of phosphates and the best effect 
was obtained with dual inoculation and the pesticides only slightly affected the growth 
and yield of the crop. 



[ 190 ] 



Recent advances and trends in ectomycorrhizal research 

H. S. THAPAR 
Division of Forest Protection, Forest Research Institute, Dehra Dun 

Inspite of the fact that mycorrhiza research has been pursued for several 
decades, it has not taken off of in a big way to attract the attention of nursery men 
and nursery managers for exploiting full potential of mycorrhiza in the production of 
superier planting stock. The thrust areas which should attract serious attentions are 
screening and selection of efficient fungi and strains, inoculum production, initiation 
of mycorrhiza in a soil system in containerized programmes, production of mycorrhizal 
plants with spores inocula (encapsulation of seeds, hydrogel bead inocula) and testing 
of field performance of inoculated nursery seedlings. While the efficacy of pure 
culture inoculation has been established, inoculation of nursery seedlings with a 
mixture of mycorrhizal fungi needs to be given a fair trial. 

The work on fungicide/mycorrhizae interaction is confined to solitary reports. 
Few studies are documented which throw light on the toxic effect of fungicides on 
mycorrhizal development in seedlings and tolerance of mycorrhizal fungi to fungicides 
jn vitro. The nitrogen fixing capability of mycorrhizal fungi is viewed with caution 
and not many reports have appeared to confirm the claim. This aspect of work has 
received scant attention and studies are warranted specially when sophisticated 
instrumentation facilities are available in all biochemical and physiological laborato- 
ries. Considerable amount of work has appeared in the past few years on biological 
suppression of root disea es in agricultural crops by VAM fungi in forest tree species, 
some attempts were made to initiate parallel studies with the ECM fungi but the work 
could not advance further. The role of ECM fungi in control of root diseases in 
genera of Eucalypts and Albizia need to be defined. Studies on ultrastructure of 
mycorrhiza to resolve differences between the various classes of mycorrhizal fungi are 
important and deserve more attention. Fungus gardens which serve as a source of 
mycorrhizal inoculum on the nursery sites need to be established in the areas where 
the density of the native mycorrhizal fungi is low. 

Inspite of considerable upsurge in mycorrhiza research in advanced countries 
and third world nations more is known about the basic metabolic functions of 
mycorrhizae than is known to correct plant maladies and effectively supply knowledge 
gained as far on a broad practical scale even without knowledge of basic answers. 
Most researchers agree that in order to justify expenditure on mycorrhiza research it 
is time to apply existing basic information on developmental efforts to solve global 

[ 191 ] 



problems of energy resources deforestations and timber shortage. The management 
system that produces high yield in agriculture and forest tree in developed nations are 
not condusive to depleted economics of growing nations as some of these systems are 
already under censure, especially in United States. The mycorrhizal technology 
developed in U.S.A. has found practical application in reclamation on waste lands, 
acid coal soils and forestation of mined areas, borrow pits with astounding success. 
The American experience convincingly establishes that some species of ectomycorrhi- 
zal fungi under certain environmental conditions are more beneficial to trees than 
other fungal species which occur naturally. Future research therefore, should be 
directed at country wide scaning, selecting, propagating, manipulating and managing 
more desirable fungal symbionts to improve tree survival and growth. Zobel (1979) 
pleaded that the major challenge to forest scientists is to generate the biological 
technologies needed to grow productive forests and remaining land now considered to 
be submarginal for economic production of either food or timber crops. Acordirg 
to Tinker (1982) unless the practical benefits of mycorrhizal inoculation are 
demonstrated convincingly in field trials and such hopes are too long deferred there 
could be a reaction amongst research managers against mycorrhiza research. 
However, when one considers the millions of hectares of potential exotic forests that 
might be established in the third world nations as well as millions of hectares of 
forests land awaiting artificial regeneration in the develop world the importance of 
such inexpensive treatments as for instance mycorrhizal inoculations becomes 
apparent and perhaps the only sound choice. 

REFERENCES 

Bakshi, B.K. 1974. Mycorrhizae and its role in forestry, Pl-480 Project Report, FRI and Colleges, 

Dehra Dun. 
Hasskayle, E. 1972. Mycorrhiza : The ultimate in reciprocal parasitism. Bio Science 22 : 

577-583. 
Thapar, H.S., Pokhriyal, T.C. 1988. Nitrogen fixation by some ectomycorrhizal fungi. International 

Conference on Research in Plant Sciences and its relevent future, 7-11, March, 

1988, New Delhi 
Tinkar, P.B. 1982. Mycorrhizae : The present position. Whither soil Research Pannel discussion 

papers. ISSS, AISS. 
Zobel, B. 1979. Growing more timber on less land. For. Farmer 38 : 15. 



[ 192 ] 



Desert plantation and mycorrhizae-current state of art 

A. VARMA, NEERAJ, R. KAUR AND A. SHANKAR 
School of Life Sciences, Jawaharlal Nehru University, New Delhi-1 10067 

The importance of VA mycorrhiza to agriculture and forest crops has been 
well documented but associations in arid and semi arid plants and wild vegetation 
have received little attention. VA mycorrhizae may be advantageous to rnycorrhizal 
desert plants where phosphorus exists as practically insoluble calcium phosphate and 
the diffusion of ions in the soils is decreased by low moisture. Mycorrhizae are an 
important consideration in maximising rangeland and arid land productivity. The 
understanding of rnycorrhizal associations of semi arid desert, rangeland vegetations, 
the distribution of rnycorrhizal fungi and soils is necessary for wise management of 
these fragile habitats. 

Recent scientific results provide data which support the hypothesis that rnyco- 
rrhizal plants are effective colonizers of disturbed habitats and that the lack of 
of rnycorrhizal fungi exert profound influences on species composition (Tommereup 
and Abbott, 1981). Ninty nine percent of the plant cover was rnycorrhizal in arid 
and semiarid habitats. Mycorrhizae are an important consideration in maximising 
rangeland and arid land productivity. The understanding of rnycorrhizal associations 
of semiarid, desert and rangeland vegetation and the distribution of rnycorrhizal fungi 
and soil is necessary for wise management of these sunbaked sand dunes (Trappe, 
1981). 

Mycorrhizal fungi directly mediate interaction between plant in atleast four 
ways (a) They allow trees to compete successfully with grasses and herbs for 
resources and they detoxify allelochemicals produced by these plants as well, (b) 
Mycorrhizae may decrease competitive interactions between the plants and increase 
the productivity of species mixture, particularly in soils where phosphorus is limiting, 
(c) Mycorrhizal hyphae link the same and different species act as a route of material 
transfer among plants. In drought stress environments legume seedlings often 
associate in disproportionate number with perennial grasses, where their survival is 
probably enhanced because of the rich concentration of mycorrhizal inocula. (d) 
Mycorrhizae and other microbes affect soil formation and structural characteristics 
by producing humic compounds, accelerating decomposition of primary minerals and 
producing organic 'glues' that bind soil particles into water stable aggregates. 
Aggregation in turn influences soil properties providing the diversity of pores necessary 
to permit both water drainage, therefore aeration (Rose, 1988; Maxel and Reid, 
1973). Through close mutual interactions between plants and soil organisms, these 

[ 193 ] 



ecosystems create the conditions that allow the systems to persist. Severing the close 
links between plants and soil has contributed to degradation of many ecosystems and 
restoring these links in an important step towards rehabilitation (Trappe and Awameh, 
1981). 

Vesicular-arbuscular mycorrhizae are cosmopolitan and almost universal in ^ 

host range. The most dominant mycorrhizal spores in arid and semi-arid regions 
were Glomus macrocarpum, G.fasckulatum, G. mosseae, Gigaspora albida, Sclerocystis 
sinuosa and Scutellospora calospora. Some spores possess very characteristic features 
not commonly encountered elsewhere. The rhizosphere of the edible cacti were 
heavily infested with ppores of Glomus macrocarpum and Sclerocystis sinuosa: They 
formed ramifying hyphae and the vesicles in the root system. 

Out of the 6507 species of angiosperms that have been studied 70% are consis- 
tently found to be mycorrhizal and 12% are apparently facultatively mycorrhizal 
(Trappe, 1987), sometimes forming mycorrhizae or sometimes not. By and large the 
plants of arid and semi-arid rangeland are mycorrhizal. It is perhaps a testament 
to the strength of a healthy link between plants and rhizosphere organisms that 
despite stressful environments, their ecosystems are not necessarily unproductive. 

Much still needs to be learnt, but one conclusion already seems warranted. 
Diversity in the plant community, the microbial community and the ecosystem as a 
whole plays a seminal role in buffering against disturbance and maintaining healthy 
links between plant and soils. Management system in these difficult terrain aimed 
at protecting diversity are an important step towards sustainable resource utilization. ■*•>» 

Studies are urgently needed for many habitats in question. 

Indigenous mycorrhizal fungi are not necessarily the best for optimum growth 
of desired forage species in a given soil. The introduction of more efficient fungi to 
a site to selectively promote desired forage species and land deserves research 
attention. 

Mycorrhizal and bacterial inocula need to be developed in two 'generations' — 
the first consisting of naturally occurring bacteria, fungi and the second consisting of 
genetically engineered microbes. The mass inoculum production must also be utilized 
and the quality of their output controlled with respect to inoculum density and 
biological activity. 

We need to understand the interaction among mycorrhizal fungus species, 
host species and environment. Future research must therefore strengthen scope to 
include the mycorrhizosphere and ecosystem and as a whole. 

The actual compounds transferred from the fungus to the host are essentially ^ 

unknown. It is proposed that glutamine, as the most abundant and first formed 
amino compound is a probable candidate (Varma, 1989). Characterization and 
regulatory role of amino compounds need elucidation. 

[ 194 ] 



The ecological importance of the enzymatic reactions at the mycorrhizal or 
hyphal surfaces has not been fully considered but undoubtedly would seem to provide 
sources of nutrient in addition to the standing concentration of the soil solution in 
the immediate locality of a hyphae or rootlet. 

REFERENCES 

Maxel, J., Reid, C. P. P. 1973. The growth of selected mycorrhizal fungi response to induced 

waterstress. Can. J. Bot. 51 : 1579- 1588. 
Rose. S. L. 1988. Above and below ground community development in a marine sand dunes 

ecosytem. Plant and Soil 109 : 215-216. 
Tommerup, I. G, Abbot, L. K. 1981. Prolonged survival and viability of VA mycorrhizal hyphae 

after root death. Soil Biol. Biochem. 13 : 141-164. 
Trappe, J. M. 1981. Mycorrhizae and productivity of Arid and Semi-Arid Rangelands. In: 

Advances in Food Producting Systems for Arid and Semi-Arid Land, Eds J. T. Manassah, 

E. J. Briskey, Acad, Press. INC, N. Y. pp. 581-599. 
Trappe. J. M , Awameh, M. S. 1981. Mycorrhizae and productivity of Arid and Semi-Arid 

rangelands. In : Advances in food producing systems for Arid and Semi-Arid land, 

Eds. J. T. Manassah, E. J. Briskey, Academic Press. N. Y. 
Trappe, J. M. 1987. Phylogenetic and ecological aspects of mycotrophy in the magnoliophyta 

(angiosperms) from an evolutionary stand point. In : Ecophysiology of vesicular- 

arbuscular mycorrhizal plants. Ed. G. Safir, CRC Press. Boca, Florida, pp. 5-25. 
Varma, A. K. 1989. Growth and some aspects of nitrogen metabolism of Gigaspora gigantea. In I 

Proc. First Asian Conf. on Mycorrhizae. Eds. A, Mahadevan, N. Raman, K. Natarajan, 

pp. 120-124. 



E 195 ] 



Vesicular-arbuscular mycorrhizal root colonization and spore production 
in maize inoculated with Glomus fasckulatum 

P. NADARAJAH AND A. NAWAWI 

Department of Botany, University of Malaya, 59100 Kuala Lumpur, Malaysia 

Surveys on the numbers and types of spores present in soil have shown that 
among the various vesicular-arbuscular mycorrhizal (VAM) fungi, Glomus fasckulatum 
(Thaxter sensu Gerd.) Gerd. & Trappe has a worldwide distribution both in agricul- 
tural and natural sites (Gerdemann and Trappe, 1974). Its occurrence is also 
widespread in Malaysia (Nadarajah and Nawawi, 1989). As an obligate symbiont, 
G. fasckulatum is a beneficial soil fungus forming associations with roots of a variety 
of agricultural crops as well as uncultivated plants. This fungus occurs in soil as 
(i) spores (singly or in loose aggregates), (ii) colonized roots in the form of hyphae, 
vesicles, coils and arbuscules or (iii) hyphe. Each of these componsnts may have the 
ability to initiate an infection (Daft et al, 1987). 

A time course study was thus conducted to determine the infectivity of the 
components of a local isolate of G '. fasckulatum and the development pattern of root 
colonization and spore production with maize (Zea mays L.) since this plant is used 
widely for routine production of spores. 

Spores of G. fasckulatum were isolated from rhizospheres of cocoa plants 
(Theobroma cacao L.) using the wet-sieving and decanting technique (Gerdemann and 
Nicolson, 1963). The pH and available Bray No. 2 P of these soils ranged from 
5.0 to 5.8 and 11 to 45 ppm, respectively (Nadarajah and Nawawi, 1989). G. 
fasckulatum was multiplied in pot cultures with maize. The growth medium consisted 
of methyl bromide fumigated garden soil : sand mixture (pH 5.3 and 11 ppm available 
P). All pot cultures were grown for 4 months in a greenhouse with normal sunlight 
and temperatures ranging from 24 to 39±2°C. Pots were fertilized weekly with 
quarter-strength Hoagland's solution without phosphorus and were watered as needed 
with distilled water. 

The fungal treatments were inoculation with (i) soil, (ii) spores, (iii) mycorrhizal 
root pieces, (iv) external hyphae, (v) vesicles or (vi) filtered washings. Soil inoculum 
(1 g) consisted of soil, spores, hyphae and mycorrhizal root fragments from plants 
grown in pots. Spore inoculum (100 spores) consisted of spores isolated from soil by 
wet sieving and decanting. External hyphae (0.5 g) were also obtained by wet-sieving 
and decanting. Root inoculum (0.5 g of chopped mycorrhizal roots) was obtained 

[ 196 ] 



by picking the root pieces from sievings, then washed free of adhering spores and cut 
into 1 to 5 mm pieces. Vesicles (100 vesicles) were removed gently from mycorrhizal 
root pieces by maceration. Noninoculated controls received leachings of the fungus 
passed through a 45 um sieve three times. 

Surface sterilized seeds of maize were germinated in moist, sterile sand. After 
10 days, seedlings were transplanted singly into polyvinylchloride bags containing 3 kg 
fumigated garden soil. For each treatment, the inoculum was placed onto a filter 
paper and wrapped around the roots of the seedlings or placed 3-5 cm below the 
seedlings. Growth conditions were the same as those for pot cultures. There were 
four replicates for each form of inoculum. 

Plants were harvested at 1, 2, 3, and 4 months after inoculation. Percentage 
mycorrhizal colonization in roots was determined by staining the roots with trypan 
blue (Phillips and Hayman, 1970) and spore numbers in soil by wet-sieving and 
decanting. 

All plants, except controls, became mycorrhizal and produced spores at 
varying levels. Although infection was observed one month after inoculation, root 
colonization by spores, external hyphae and vesicles were much lower than that by 
soil or root inocula. However, by 4 months colonization levels by soil, root and 
spore components were over 80% while the external hyphae and vesicle components 
had 45 and 65%, respectively. 

Sporulation pattern followed similar trends 4 months after inoculation. Of the 
various components tested, soil and root inocula started producing spores at 2 months 
with higher spore production occurring at 4 months with soil inoculum. 

The soil component was more effective as inoculum for root colonization and 
spore production than the other components. This is because soil inoculum contains 
various forms of propagules (spores, mycorrhizal root fragments and external 
hyphae) which are capable of initiating an infection. Root colonization levels 
developed more quickly from colonized root pieces than from spores. The initial 
delay in spore infection may be related to factors such as age and viability of spores 
or because some spores produce a pre-infection phase in soil (Powell, 1976). Internal 
vesicles are often present in roots colonized by G.fasciculatum. These are considered 
to be storage organs and may become thick-walled and function as spores 
(Gerdemann and Trappe, 1974). In this study, vesicles were infective and colonized 
roots. This confirms observations by Biermann and Linderman (1983) who suggested 
that vesicles contribute to inoculum potential of mycorrhizal roots. External hyphae 
produced the lowest levels of colonization. This concurs with the findings of Daft 
et al. (1987), where the hyphal fragments were least effective in establishing VAM 
with Medicago sativa. 

[ 197 ] 



Powell (1976) suggested that the different infective patterns of VAM fungi 
were probably related to the amount of nutrient reserves in the specific inoculum 
component. The varying levels of development of VAM root colonization could 
also be attributed to the inoculum concentration of each component being not 
optimized. As there are conflicting reports on the infectivity and effectiveness of 
components of VAM fungi with other hosts (Biermann and Linderman, 1983; Daft 
et al, 1987; Powell, 1976), further research is necessary to determine the inoculum 
potential of components of other VAM fungi. 

REFERENCES 

Biermann, B, Linderman, R. G. 1983. Use of vesicular-arbuscular mycorrhizal roots, inraradical 

vesicles and extraradical vesicles as inoculum. Trans. Brit. Mycoi. Soc. 95 : 97-105. 
Daft, M. J., Spencer, D., Thomas, G. E 1987. Infectivity of vesicular arbuscular mycorrhizal 

inocula after storage under various environmental conditions. Trans. Brit. Mycol. Soc. 

88 : 21-27. 
Gerdemarm, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted from 

soil by wet-sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-244. 
Gerdemann, J. W., Trappe, J. M. 1974. The Endogonaceae in the Pacific Northwest. Mycologia 

Memoirs 5 : 1-76. 
Nadarajah, P., Nawawi, A. 1989. Vesicular-arbuscular mycorrhizal fungi associated with Theobroma 

cacao L. in Malaysia. In : Proceedings of the First Conference on Mycorrhizae, Eds. A. 

Mahadevan, N. Raman, K. Natarajan, Madras, India, pp. 238-240. 
Phillips, J. M., Hayman, D. S. 1970. Improved procedures for clearing roots and staining parasitic 

and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Trans. Brit. 

Mycol. Soc. 55: 158-161. 
Powell, C. LI. 1976. Development of mycorrhizal infections from Endogone spores and infected 

root segments. Trans. Brit. Mycol. Soc. 66 : 439-445. 



[ 198 ] 



Development of ectomycorrhizae on pine and its effect on the growth 
of Pinus kesiya under different moisture regimes 

RAJKUMAR, G. D. SHARMA AND R. R. MISHRA 

Department of Botany, School of Life Sciences, North-Eastern Hill University, 

Shillong-793 014 

It is well known that water is a universal solvent. All physiological and 
biochemical activities are governed by the availability of water in living system. 
Microbial activities in soil are also influenced by the availability of moisture in soil. 
Water in soil may influence the mycorrhizal formation (Bakshi, 1974). Mycorrhizal 
plants can also tolerate more water stress conditions than non-mycorrhizal ones 
(Parke et al , 1983). An attempt was, therefore, made to study the influence of soil 
moisture on the colonization and development of mycorrhiza with pine seedlings. 

The experiment was conducted in glass house conditions. Plastic pots of 15cm 
diameter were filled with sterilized sandy loam soil (pH 5.2, Organic matter 3.5%, 
N 0.094%, P 0.021% and K 0. 183%). Pine (Pinus kesiya Royle Ex Gorden) seedlings 
of 4 cm length raised aseptically in laboratory, were transferred to the pots. There- 
after 10 days, the spore suspension of Boletus edulis and Scleroderma aurantium 
(1.3x 10" spores/ml) was inoculated. Uninoculated seedlings of pine were maintained 
as control. Three levels of moisture content i. e. 10, 30 and 55% were maintained. 
Seedlings were harvested after 6 months with soil attached to root system. Acid 
phosphatase activity in soil and root surface was estimated by the method of Dodd 
et al. (1987). Colonization of mycorrhizal fungi was studied under stereobinocular 
microscope. Growth of mycorrhizal and nonmycorrhizal seedlings was measured. 

Colonization of both mycorrhizal fungi on pine seedlings differed with different 
moisture levels. S. aurantium showed significantly higher colonization at 30% moisture 
level than other levels of moisture. However, B. edulis exhibited better symbiosis at 
55% moisture content. Lowest moisture level (10%) inhibited colonization of both 
the mycorrhizal fungi. 

Shoot growth of seedlings at 10 and 30% moisture content was insignificantly 
more in seedlings inoculated with S. aurantium than control ones. At 55% moisture 
level, B. edulis inoculated seedlings had significantly enhanced growth than control. 
Shoot and root dry weights of seedlings were observed better at medium moisture 
level with S. aurantium. 

[,199 ] 



Maximum acid phosphatase activity in mycorrhizal roots and soil was observed 
in pine seedlings inoculated with S. aurantium at medium moisture level, whereas 
B. edulis inoculated roots and soil showed better activity at 55% moisture level. 
Mycorrhizal fungi enhanced the growth of pine seedlings more at low as well as high 
levels of moisture content differently than uninoculated seedlings. 

The colonization of S. aurantium was reduced at highest moisture level which 
may be due to low hyphal entry points in root epidermis, resulting into the reduced 
infection (Reid and Mekal, 1977). Mycorrhizal plants have been reported to grow 
better in low moist condition than uninoculated ones due to their capacity to explore 
the new or larger soil zone through their extended hyphal root system (Ponder, 1983). 
B. edulis was better adapted to high moisture level than S. aurantium which suggested 
that the later one is highly aerobic fungus than the earlier one. Another reason for 
less efficiency at high moisture level may be attributed to the higher dilution rate of 
nutrients resulting in increase in acidity of soil which might have inhibited the growth 
of S. aurantium and stimulated B. edulis. 

Acid phosphatase activity of the surface of mycorrhizal roots and in rhizos- 
pheric soil was correlated with colonization of mycorrhizal fungi and has been 
affected by the aeration at high moisture level and temperature of soil. 

REFERENCES 

Bakshi, B. K. 1974. Mycorrhiza and Its role in forestry, PL 480 Report, Forest Research Institute & 

College, Dehradun. 
Parke, J. L., Llnderman, R. G., Black, C. H. 1983. The role of ectomycorrhlzae In drought 

tolerance of Douglas-fir seedlings. New Pythol. 95 : 83-95. 
Dodd, J. C, Burton, C. C, Burn, R. G, Jeffries, P 1987. Phosphatase activity associated with the 

roots and rhizosphere of plants infected with vesicular arbuscular mycorrhizal fungi. 

New Phytol. 107 : 163-172. 
Ponder, F. 1983. Soil moisture levels and mycorrhizal infection in black walnut seedlings. Soil 

Sci. Plant Anal. 14:507-511. 
Reid, C. P. P., Mekal, J. G. 1977. Water stress effect on root exudation by lodgepde pine. Soil 

Biol. Biochem. 9 : 417-421. 



[ 200 ] 



\ 



Identification of endogonaceous fungi from Delhi 

Q. Z. KHAN AND A. K. SARBHOY 
Division of Mycology and Plant Pathology, IARI, New Delhi-1 10012 

Ten soil samples were collected from three different soil types from Indian 
Agricultural Research Institute fields, New Delhi. These soils were analysed for 
their pH, moisture contents and carbon and nitrogen ratio. 

Twenty different species belonging to six genera of Endogonaceae viz., Glomus, 
Gigaspora, Endogone, Entrophospora, Acaulospora and Complexipes were collected. 
Acaulospora trapei, A. scrobionta, A. spinosa, A. leavis, Endogone flammicorona, E. 
tactifolia, Entrophospora enfrequence, complexipes moniliformis, Gigaspora decipens, G. 
nigra, Glomus frag His and G. wum, were added for the first time from India. Several 
Glomus species were also recorded which are quite dominant in the area. 



[ 201 | 



Interaction between Rhizobium (cow pea miscellany) and mycorrhizal 
fungi and their stimulatory effects on Acacia nilotica (L.) Del. 

PRAM1LA SHARMA, R. NIRANJAN, BANWARILAL AND V. M. RAO 
Department of Botany, University of Rajasthan, Jaipur-302017 

VAM occur widely under various environmental conditions and are found in 
association with a number of leguminous plants. VAM fungi which constitute a 
group of important soil micro-ogranisms are ubiquitous throughout the world and 
are known to improve the plant growth through better uptake of nutrients. They 
also improve the activity of N 2 fixing organisms in the root zone (Mosse et al., 1976). 

It is found that simultaneous inoculation of legumes with Rhizobium and VAM 
causes synergistic beneficial effects (Bagyaraj et al., 1979). The present report deals 
with the results of pot experiments to assess the effect of inoculating seeds of Acacia 
nilotica with Rhizobium sp. (cowpea miscellany) and soil with VAM fungi (Gigaspora 
margarita and Glomus fasciculatum) singly or in combination on dry matter 
production, nodulation, N a -fixation (N a -ase activity) and nutrient uptake by plants 
under sterile conditions. 

Plants were inoculated with 5 ml/seedling of rhizobial inoculum containing 
3xl0 9 cells/ml (AN-R). Mycorrhizal spores were selected through the wet sieving 
and decanting technique (Gerdemann and Nicolson, 1963). The mycorrhizal 
inoculum consisted of a mixture of spores of endophyte belonging to G. nargarita and 
G. fasciculatum on an average 50 VA spores were included in each pot. Inoculum 
contained about 250 spores per 50 g soil. A thin layer of inoculum (50 g) was placed 
below the surface before sowing seeds. Soil without any microbial additions served 
as control. Experiment was conducted during May to September months. Eight 
different treatment combinations were used. The total plant and nodular proteins 
were estimated according to the method of Lowry et al. (1951). 

Quantitative estimation of nodular leghaemoglobins was done as per haemo- 
chromogen method of Hartee (1957). Nitrogen content was estimated following 
Kjeldahl digestion method (Bremner, 1960) and phosphorus was determined according 
to a modified molybdate method (Golterman, 1970). The total soluble sugars were 
measured by phenyl-sulphuric acid method (Dubois et al., 1951) and the total 
chlorophyll content was estimated following the method of Arnon (1949). 

The height of plants was significantly more in combinations of Rhizobium and 
VAM as compared to Rhizobium or VAM treatments alone and also with that of 

[202 ] 



\ 



control treatment. Dry weights of plants also showed the same response to the 
treatments. 

Similarly, dual infection with Rhizobium and VAM resulted in best nodulation. 
Number and weight of nodules in this treatment were significantly more than that of 
Rhizobium alone. Amount of leghaemoglobin in root nodules, treated with Rhizobium 
alone or in combination with VAM was almost the same. 

The nitrogenase activity (N 2 -flxation) by acetylene reduction assay in the root 
nodules obtained from the plants inoculated with Rhizobium plus VAM was higher 
than Rhizobium inoculated alone. 

All plants were tested for sugar, chlorophyll and protein contents and it was 
seen that combined inoculum gave the best results. Similarly, the values for N and 
P were the highest in plants which had received the combined inoculum of Rhizobium 
and VAM. 

The parameters selected to examine the effect of Rhizobium and VAM either 
individually or in combination were plant height, weight, nodule number, nodule 
weight, nodule protein, Lb content in nodules, plant protein, sugar and chlorophyll 
contents and uptake of nutrients (N and P). Data clearly indicate that dual infection 
resulted in better growth and nodulation in Acacia nilotica. This observation is in 
confirmity with earlier work of Brgyaraj et al. (1979) on soyabean. In view of these 
observations, it may be logical to conclude that Glomus and Gigaspora spores used in 
the present investigation are very effective with Acacia nilotica. 

In the present study conducted in sterilized soil Rhizobium with VAM 
stimulated nodule number, nodule weights, total leghaemoglobin content and 
N 2 -fixation (N 2 -ase activity) in Acacia nilotica. This is in confirmity with the 
observations made in legumes by Varma (1979). 

Uptake of N and P by inoculated plants (singly and dually inoculated) was 
significantly more than that of uninoculated controls. The dually infected plants 
probably derive considerable benefits from the physiological activities of the 
endophytes and the major elements N and P are mitigated by the endophytes. 

REFERENCES 

Arnon, D. I. 1949. Copper enzymes in isolated chloroplasts polyphenoloxidase in Beta vulgaris. 

Plant Physiology 24 : 1-15. 
Bagyaraj, D. J , Manjunath, A , Patil, R. B. 1979. Interaction between a VA mycorrhizae and 

Rhizobium and their effects on soyabean in field. New Phytol. 82 : 141-145. 
Bremner, J. M. 1967. Determination of nitrogen in soil by Kjeldahl method. /. Agric. Sci. 

55 : 11-33. 
Dubois, M., Gillcs, K., Hamilton, J. K., Robers, P. A., Smith, F. 1951. A colorimetric method 

for the determination of sugars. Nature 168 : 167. 

[ 203 ] 



Gerdemann, J. W., Nicolson, T. H. 1963. Spores of mycorrhizal Endogone species extracted from 

soil by wet sieving and decanting. Trans. Brit. Mycol. Soc. 46 : 235-244. 
Golterman, H. L Ed. 1970. Methods for chemical analysis of fresh water. IBP Handbook No. 8, 

Blackwell Sci. Publication Oxford, Edinburgh, pp. 76-78. 
Hartee, E. F. 1957. Haematin compounds. In : Modern methods of plant analysis, Eds. R. Peach, 

M. V. Tracey, Springer Verlag 4 ; 197-245. 
Lowry, O. H., Rosebrough, A. L., Farr, Randall, R. J. 1951. Protein measurement with the 

Folin-Phenol reagent. J. Biol Chem. 193 : 265-275. 
Mosse, B., Powell, C. L., Hayman, D. S. 1976. Plant growth responses to vesicular arbuscular 

mycorrhiza. IX. Interaction between VA mycorrhiza, rock phosphate and symbiotic 

nitrogen fixation. New Phytol. 76 : 331-342. 
Varma, A. K. 1979. Vesicular arbuscular mycorrhiza and nodulation in soyabean. Fdia 

Microbiol 24:501-503. 



t 204 ] 



\ 



Studies on the effect of Rhizobium (cowpea miscellany) and 
endomycorrhizal interaction in Dalbergia sissoo (Roxb.) 

R. NIRANJAN, PRAMILA SHARMA, BANWARILAL AND V. M. RAO 
Department of Botany, University of Rajasthan, Jaipur-302004, India 

The leguminous plants can form two types of symbiotic associations with 
microorganisms. One with Rhizobium sp. involved in N 2 -fixation, the other with 
VAM fungi, concerned with the uptake of P and other nutrients (Crush, 1974). It is 
now established that the enhanced growth of plant is due to absoption of ions 
especially P by the fungus from the soil and subsequent transfer in plant (Hayman 
and mosse, 1972). Inoculation of legumes with VA mycorrhizal fungi can stimulate 
nodulation and N 2 -fixation (Mosse, 1981). 

In the present study, response of Dalbergia sissoo to inoculation with Rhizobium 
sp. (cowpea miscellany) and VA mycorrhiza (Glomus fasciculatum) is presented. 

The surface sterilized seeds of Dalbergia sissoo, inoculated with corresponding 
Rhizobium sp. (cowpea miscellany) containing 4 xlO 8 cells, were sown in pots filled 
with sterilized sandy loam soil (2 kg each). The endomycorrhizal spores as mycorr- 
hizal inoculum, to provide 250 per 50 g soil was also added in each pot. Soils with 
no microbial additions served as control. Three seedlings were maintained in each of 
the five replicates of the treatment. The pot trial was carried out from April to 
August months, using diffrent treatment combinations. 

The total plant and nodular proteins were estimated according to the method 
of Lowry et al. (1951). Quantitative estimation of nodular leghaemoglobin was done 
as per haemochromogen method of Hartee (1957), nitrogen content of plant was 
estimated following Kjeldahl digestion method (Bremner, 1967). P was determined 
acording to a modified molybdate method (Golterman, 1970). The total soluble 
sugars were measured by phenol sulphuric acid method (Dubois et al., 1951). Total 
chlorophyll content was estimated following the method of Arnon (1949) and N 2 -ase 
activity of nodules were measured by Acetylenereduction technique with the help of 
Gas chromatograph. 

Analysis of growth in terms of shoot and root length, their dry weight, total 
chlorophyll content and total plant protein content indicates that, mycorrhizal and 
rhizobial plants grew much better than the untreated ones. The differences were very 
significant for control and rhizobial p'ants and also between mycorrhizal and 
Rhizobium plus mycorrhiza inoculated plants. The maximum growth was recorded 
in the double inoculated plants. 

[ 205 ] 



/ 



The dual inoculation considerably stimulated root nodulation (nodule number, 
fresh and dry wt., nodule protein and nodule leghaemoglobin) than plants inoculated 
with Rhizobium alone. The nitrogenase activity of nodules by Acetylene Reduction 
Assay (ARA) was also enhanced in double inoculated plants than with single inocula- 
tion {Rhizobium alone). Further, the specific activities of the ammonia assimilation 
enzymes viz., giutamine synthetase (Mn+ 2 dependent transferase assay), alanine 
aminotransferase and aspartate aminotransferase, except giutamine dehydrogenase 
were higher in nodules of double inoculated plants than of Rhizobium inoculation 
alone. 

The uptake of elements N and P was also affected in plants inoculated by 
Rhizobium and VA mycorrhiza. Higher values were obtained in plants with double 
inoculations in comparison to single inoculation and uninoculated control. 

The results clearly indicate that the dual inoculation of Rhizobium and VA 
mycorrhiza promoted more nutrient uptake (N and P) and consequently the growth 
in Dalbergia sissoo. This is in confirmity with earlier work (Abbott and Robson, 
1982). Even response of plants to single inoculation with mycorrhiza or Rhizobium 
was better over inoculated control. 

In the present investigation the nodulation in terms of nodule number, dry 
weight of nodules, total leghaemoglobin content and nitrogenase activity (N 2 -fixation) 
in nodules was also enhanced in Dalbergia sissoo inoculated with Rhizobium and 
VA mycorrhiza. This is in keeping with the earlier observation made in legumes 
(Varma, 1979). Further, the specific activity of ammonia assimilation, viz., giuta- 
mine synthetase, aspartate amino transferase and alanine amino transferase was 
considerably stimulated as a result of dual interaction between Rhizobium and VA 
mycorrhiza. 

REFERENCES 

Abott, L K., Robson, AD. 1982. The role of vesicular arbuscular mycorrhizal fungi in agriculture 

and the selection of fungi for inoculation. Aust. J. Agric. Res. 33 : 389-408. 
Anion, D.I. 1949. Copper enzymes in isolated chloroplasts polyphenoloxidase in Beta vulgaris. 

Plant Physiology 24 : 1-15. 
Bremnar, J.M. 1967. Determination of nitrogen !n soil by Kjeldahl method. J. Agric. Sci. 55 : 

11-33. 
Crush, J.R. 1974. Plant growth responses to vesicular-arbuscular mycorrhiza. VII. Growth and 

nodulation of some herbage legumes. New Phytol. 73 : 743-756. 
Dubois, M„ Gilles, K., Hamilton, J.K., Rebers, P.A., Smith, F. 1951. A colorimetric method 

for the determination of sugars. Nature 168 : 167. 
Golterman, H L. Ed. 1970. Mothods for chemical analysis of fresh waters. IBP Handbook no. 

8 Biackwell Sci. Publication, Oxford, Edinburgh, pp. 76-78. 
Hartee, E F. 1957. Haematin compounds. In : Modern methods of plant analysis Eds. R. 

Peach, M.V. Tracey, Springer ^Verlag 4 : 197-245. 

[ 206 ] 



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Hayman, D.S., Mosse, B. 1972. Plant growth response to vesicular arbuscular mycorrhiza. III. 

Increased uptake of labile P from soil. New Phytol. 71 : 41-47. 
Lowry, O.H., Rosebrough, A.L. Farr, Randall, R J. 1976. Protein measurement with the Folin- 

phenol reagent. /. Biol. Chem. 193 : 265-275. 
Mosse, B. 1981. Vesicular arbuscular mycorrhiza research for tropical agriculture. Research 

Bulletin 194 : 1981 (2 M). 
Mosse, B , Powell, C.L., Hayman, D.S. 1975. Plant growth response to vesicular arbuscular 

mycorrhiza. IX. Interaction between VA mycorrhiza, rock phosphate and symbiotic 

nitrogen fixation. New Phytol. 76 : 3316-342. 
Varma, A.K. 1979. Vesicular arbuscular mycorrhiza and nodulation in soyabean. Folia Microbiol. 

24 : 501-S03. 



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Nitrogen and carbon nutrition studies of endophytes of ophioglossales 

L. N. NAIR 
Department of Botany, University of Poona, Pune-41 1 007 

Having established the identity of the endophytes Ophioglossum reticulatum L., 
Q. pedunculosum and Botrychium virginianum (Nair, 1988) it was necessary to ascertain 
the role they play in the nutritional cycle of the plant. Hence some aspects of their 
nutrition were studied using different nitrogen and carbon sources. 

Most of the ammonium salts did not support the growth of Fusarium 
oxysporum-A. There was no sporulation and the hyphae were abnormal and appeared 
beaded. The terminal cells of these hyphae were elongated. Ammonium nitrate 
was slightly better and the growth with ammonium tartrate and ammonium citrate 
was better compared to other salts of ammonium, especially in solid cultures. With 
potassium nitrate there was normal and good growth and sporulation. 

The nitrogen sources selected for both cultures were, ammonium oxalate, 
casein, urea, asparagine, sodium nitrate and ammonium nitrate. 

In submerged cultures ammonium nitrate proved to be the best source of 
nit/ogen. In these cultures almost all sources of nitrogen produced normal hyphae, 
though sporulation was absent. 

In stationary cultures ammonium nitrate gave the best growth. Sources of 
other ammonium salts and casein unlike that in solid media, were good sources of 
nitrogen. The hyphae also were normal and sporulated, though in ammonium 
oxalate and ammonium nitrate few abnormal hyphae with swollen cells having dense 
cytoplasm were observed. The pH of the medium was 3 after 144 hours of growth. 

In Fusarium oxysporum-B also ammonium chloride, ammonium oxalate and 
ammonium sulphate produced beaded haphae which did not sporulate. However, 
ammonium citrate, ammonium tartrate and ammonium nitrate supported the growth 
of this species with sporulation. Casein, like control, had very feeble growth and 
lacked sporulation. Asparagine, glycine, urea, peptone, sodium nitrate and potassium 
nitrate proved to be very good sources both for growth and sporulation. Trpptophane 
did not show very good growth. 

In submerged cultures ammonium nitrate was the best source of nitrogen 
though sodium nitrate and urea also supported comparatively better growth. The 
pH went down to 3 from 5.5. 

t 208 ] 



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In broth cultures, asparagine was the best source of nitrogen. Next to it 
were ammonium oxalate, sodium nitrate, ammonium nitrate, urea and casein in 
prefering their sequence. 

Fusarium solani colonies appeared reddish yellow in colour and had stunted 
growth in ammonium chloride, ammonium oxalate, ammonium sulphate, ammonium 
tartrate and ammonium citrate. Growth actually started after 96 hours and the 
hyphae were abnormal, beaded terminating in long cells. There was no sporulation. 
However, ammonium nitrate did not produce abnormal hyphae though there was no 
sporulation. Casein had slightly better growth, though the colonies did not show its 
normal cotony growth, tryptophane, glycine, asparagine, urea, peptone, sodium 
nitrate and potassium nitrate, supported very good growth and sporulation though 
potassium nitrate and urea were the best sources. 

In submerged cultures sodium nitrate gave the best results with asparagine and 
potassium nitrate the fungus did grow but the dry weight of the mycelium was less. 
Urea was a good source for the growth of this fungus in stationary broth cultures. 

In case of Fusarium oxysporum-A all the thriteen sources of carbon tried proved 
to be good sources for the growth. The growth of hyphae started and was visible 
even after 48 hours of incubation. Out of the various sources, maltose proved to 
be the best source of carbon. For broth cultures sucrose, dextrose and starch were 
selected. For submerged and stationary broth cultures starch gave better growth 
though in solid cultures there was comparatively less growth. This indicates that in 
presence of aeration and agitation, polysaccharides are better utilized. 

Fusarium oxysporum-B also showed good growth in all the carbon sources. 
However, sucrose and maltose were the best amongst the lot. In both submerged and 
stationary cultures starch showed better growth. 

Fusarium solani showed good growth in all the thirteen carbon sources tried. 
Amongst the thirteen carbon sources, maltose and sorbitol were better sources. 
Sucrose and dextrose gave good growth in broth cultures. 

REFERENCES 

Nair, L. N. 1988 Endolrophic mycorrhizae in Ophioglossales. In : Mycorrhizae for Green Asia, 
Eds. A. Mahadevan, N. Raman, K. Natrajan, CAS in Botany, Univ. of Madras, 
pp. 82-84. 



t 209 ] 



Distribution of VAM in Tamil Nadu 

V. GANESAN, B. BALAJEE, C. GOPALAKRISHNAN AND A. MAHADEVAN 
CAS in Botany, University of Madras, Madras-600 025 

A survey on the distribution of VAM in coastal and plain of Tamil Nadu was 
made. Rhi70sphere soils and root samples from different areas were screened for 
VAM spores and VAM infection, respectively. Of the 203 samples screened, 121 
displayed different degrees of infection ranging from 10 to 100%. This includes 35 
plants with 0-20% infection, 33 with 21-40%, 20 with 41-60%, 12 with 61-80% 
and 21 with 81-100%. The identified VAM species were Gigaspora albida, G. 
margarita, Glomus aggregation, G. ambisporum, G. citricolum, G. claroideum, G. 
fasciculatum, G. intraradices, G. occultum, G. pustulatum and G. tenerum which 
occurred at 3-17% frequency. Gigaspora Candida, Glomus australe, G. botryoides, G. 
clarum, G. deserticola, G. dimorphicum, G. mosseae and G. multisubstensum had a 
frequency of 2%. However, spores of Acaulospora longula, A. myriocarpa, A. 
icolsonii, Glomus albidum, G. hetersporum, G. pansihalos and sclerocystis clavispora were 
less frequent (1%). 

Root samples which showed heavy infection (90-100%) were used to inoculate 
onion (Allium cepa) in pots containing sterile soil. Twenty five days after inocula- 
tion, the onion roots were screened for VAM infection and rhizosphere soils for 
spores. Infected roots of Catunaregam spinosa devloped 100% infection in onion. 
Scilla indica developed 80% infection, Bauhinia racemosa 75%, Lepidogathis sp. and 
Bulbostylis barbata 65%, Caralluma adscendens 60%, Dentella repens and Spermococe 
articularis 55%, Sesamum laciniatum 50%, Asystasia gangitka 35% and Justicia 
tranguebariensis 30%. The onion roots did not develop VAM infection when 
inoculated with infected roots of Cleome viscosa, Asperagus recemosus, Borreria hispida 
and Sida cordata. The VAM spores isolated from rhizosphere soils of the test plants 
are listed below. In parantheses are the host plants whose roots served as inoculum. 
Gigaspora albida (Asystasia gangetica, Catunaregam spinosa), Glomus aggregatum 
(Cleome viscosa), G. ambisporum (Asparagus racemosus, Bulbostylis barbata, Cleome 
viscosa, Detella repens, Scilla indica), G. claroideum (Dentella repens, Sesamum 
laciniatum), G. constrictum (Sida cordata, Spermococe articularis), G. fasciculatum 
(Catunaregam spinosa), G. leptotichum (Caralluma adscendens) , G. pustulatum (Justicia 
tranguebariensis), G. reticulatum (Bauhinia recimosa), Sclerocystis microcarpos 
(Borreria hispida). 



t 210 ] 



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AUTHOR INDEX 



Adholeya, A. 53 
Ahmad, A. 115 
AH, S. S. 24 
i Atwal, A. 74 

Baghel, P. P. S. 118 

Bagyaraj, D. J. 25, 35, 68, 76, 113 

Bais, R. S. 103 

Balajee, B. 210 

Bareen, F. 1 

Behl, H. M. 122, 137 

Bhandari, A. R. 47 

Bhatti, D. S. 118 

Boonyuen, S. 49 

Chalermpongse, A. 49 

Champawat, R. S. 141 

Chandra, S. 130 

Chaudhuri, S. 7 

Chhabra, M. L. 135, 150, 178, 186 

Christine, Z. A. 78 

Chulan, A. H. 78 

Dalai, S. 164 
Devi, G. U. 144 
Dwivedi, A. 59, 167 

Ganesan, V. 210 
Gaur.A. C. 105, 190 
George, B, 100 
Gopalakrishnan, C. 210 
Gopalakrishna, M. N. 113 
Govindasamy, V. 98 
Gupta, M. L. 115 
Gupta, N. 24 
Gupta, P. P. 135 
Gupta, R. K. 61 
Gupta, R. P. 165 
Gupta, S. L. 184 



Harini Kumar.IC M. 20 
Hippalgoankar, K. V. 164 
Hiremath, P. C. 20 

flag, L. L. 94 

Indi, D. V. 146, 157 

Indira, P. 73 

Jacob, A. 100 

Jalali, B. L. 118, 135, 150, 172, 178, 186 

Jamil, K. 171 



115 



Janardhanan, K. K. 
Jha, B. N. 66 
Jha, D. K. 37, 63 
Johri, B. N. 57, 61 

Kale, P. N. 157 
Kandasamy, D. 11, 126, 133 
Kapoor, A. 139 
Kaur, R. 44, 160, 193 
Kaushik, P. 22 
Kehri, H. K. 130 
Khadge, B. R. 94 
Khan, Q. Z. 201 
Khanna, S. 53 
Konde, B. K. 146, 157 
Kotoky, R. 29 
Kshattriya, S. 37, 63 
Kumar, P. R. 135 
Kumar, R. 199 
Kumar, S. 22 
Kumari, K. 57 

Lakhanpal, T. N. 27, 128 
Lakshman, H. C. 40 
Lai, B. 202, 205 

Mahadevan, A. 210 
Mahajan, K. C. 188 



/ 



Mallesha, B.C. 68 
Manoharachary, C. 18 
Mathew, J. 44, 160 
Mehrotra, R. S. 160 
Mehta, K. 47 
Mew, T. W. 94 
Mishra, D. P. 57 
Mishra, R. R. 37, 63, 66, 199 
Misra, P. N. 122 
Mohandas, S. 55 
Mohankumar, V. 182 
Mukerji, K. G. 139 

Nadarajah, P. 196 
Nair, L. N. 208 
Nair, S.K. 100 
Narayanan, R. 11, 126 
Nasim, G. 4 
Natarajan.K. 98 
Nawami, A. 196 
Neeraj 44, 160, 193 
Negi, M. 109 
Niranjan, R. 202, 205 
Nirmala, C. B. 182 

Oblisami, G. 126, 155 
Padma, T. M. R. 133 
Padmavathi, T. 10 
Pai, G. 25 
Pandey, S. 117 
Patil, C. V. 20 
Pawar, S. E. 162 
Perrin, R. 124 
Potty, V. P. 73 
Prasad, T. G. 25 
Punj, V. 165 

Raghavendra, S. 40 
Rai, R. P. 148 
Rajagopal, D. 171 
Ramakrishnan, B. 61 
Ramaraj, B. 107 
Rana, J. P. S. 105, 190 
Rangarajan, M. 11, 126 
Rao, A. V. 42 



Rao, V. M. 202, 205 
Rao, V. P. 162 
Rathi, S. K. 31 
Raverkar, K. P., 47, 167 

Reddy, C. N. 103 
Reddy, M. S. B. 68 

Sagar, A. 128 
Sampangiramaiah, K. 124 
Santhanakrishnan, P. 155 
Sarbhoy, A. K. 201 
Sekhon, B. S. 74 
Sengupta, A. 7 
Shad, O. 128 
Shaji, G. T. 78 
Shankar, A. 44, 100, 193 
Shanmugam, N. 107 
Sharma, B. M. 13 
Sharma, G. D. 37, 63, 66, 199 
Sharma, P. 202, 205 
, Sharma, S. K. 22 
Shroff, V. N. 175, 188 
Shukla, B. N 33 
Sidhu, O. P. 122 
Singh, B. M. 13 
Singh, G. S. 152 
Singh, H. 180 
Singh, H. D. 29 
Singh, H. P. 120 
Singh, L. 31 
Singh, M. 51, 70 
Singh, O. S. 180 
Singh, R. 74 

Singh, R. P. 150, 178, 186 
Singh, R. S. 96, 180 
Singh, S. N. 80, 162 
Singh, V. K. 117 
Singh, Y. P. 96 
Sitaramaiah, K. 96, 144 
Sivaprasad, P. 100 
Sonar, K. R. 146 
Sreenivasa, M. N. 35 
Subhashini, D. V. 102 
Sulochana, T. 18 



Tarafdar, J. C. 42 Vasanthakrishna, M. 113 

Thakur, M. 27 Veeraswamy, J. 10 

Thapar, H. S. 16, 111, 191 Venkataramanan, M. N. 29 

Thapar, S. 74 Venkateswarlu, K. 10 

Tilak, K. V. B. R. 51, 59, 70, 87, 109, vidhyasekaranj p. 9l 

167 Vijayan, A. K. Ill 

Uniyal, K. 16 Vyas, A. 188 

Vanjare.N. 33 Vyas, S. C, 175, 188 

Varma, A. 44, 160, 193 Wani, P. V. 157 



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